"Transposing" sheet-music             (A testimonial! > here)
Please read before proceeding: There are many sites on the Internet that now offer downloadable / printable  sheet-music. Some of those sites can even  let you choose what key you want it in. (What does 'key' mean?) (I have tested a few sites and the quality and accuracy of the transposed music is usually very good!) 

Rates are VERY cheap compared to the custom services I offer below. (economies of scale etc.) I suggest you try those sites first, before considering the personal options I offer below.
Feel free to book a session to consult with me to find out what key the song should be in for you before you buy as most of these sites only permit you to download / print the music once, in a particular key.
Some sites to try:

http://www.musicroom.com.au Aussie site! Aussie prices! Often cheaper than foreign sites.

http://www.sheetmusicdirect.com  (You can transpose to your key after download)

http://www.sheetmusicnow.com  (mainly classical NO transpose)

http://www.online-musiclibrary.com (mainly classical)

http://www.sheetmusicscore.com 
(You can transpose to your key after download)

Or try a Google search on 'download sheet music'      (My Sheet Music links page)

NOW!  If none of the above options work for you:
AVERAGE COST FOR TRANSPOSING MUSIC AT SONGRISE:
About $30-35 AUD for a full page, of transposed sheet music
I am talking of the standard vocal score here- melody line, and simple piano accompaniment.
the form that most pop songs and song folios from musicals are printed in.
Price may vary, less or more! 
Why? See 'Transposing' article below for explanation.
The cost of all of this is about my time involved.
The quicker I can do it, the cheaper it will be!
So it is best to cut corners where we can. Before assessing cost,
I usually do a 'test' version of a page or two.
If I don't have the music you are wanting transpose,
you will have to send me the music you want me to 'test'.
THE QUALITY AND TYPE OF IMAGE YOU SEND ME IS IMPORTANT!

1. Please scan original SHEET MUSIC as a BLACK x WHITE image using FAX or BLACK/WHITE (TEXT) setting. NOT grey-scale or ANY of the 'photo' or 'illustration' or 'picture'  settings. Check your scanner configuration for this info Please scan at about 400dpi - fairly dark exposure - but not black blotches everywhere!   The image you get should look a bit like a FAX (but better quality) meaning just black and white - not shades of grey - and NOT Colour!

2. Please make sure scan goes right to the edges of the music. Music should not 'go off the page' It is important that no bits of the score are missing, (as much as possible anyway)

3. Make sure that music is lying completely FLAT when you scan it.  No 'black' blobs where music wasn't touching the glass of the scanner 4. If emailing, please send as PDF (preferably) or GIF. (avoid JPEG  or JPG) If sending by ordinary post, send the original music or a good quality photo-copy.
'Transposing'
This refers to the playing or singing of music in a different key other than the written key of the sheet music. This may require that the sheet music for a particular piece of music to be written out in a different key so that it can be read easily. (What does 'different key' mean?)  
In the good old days, many musicians could do this "at sight", meaning  you could put a piece of sheet music down in front of them in a particular key, and they would automatically change the key to the one you wanted, while they were actually playing! There was a time when this skill was taken for granted, and anybody who wished to be a professional accompanist would need to be able do this fairly well.  However times have changed. Many talented people do have the ability to do this still, but it is rare, if you find one, keep their phone number!) and these days, especially in the audition situation, you'll be expected to bring sheet music in the key that you wish to sing your song.  "How do I know if I need the sheet music to be tranposed for me to sing it?

This means that you may have to arrange for the music to be written out again in your preferred key. Once again, in the good old days this was done by hand, it took some time, and the results were not always easy-to-use, because the music was hand written, and no matter how good the music copyist was, it still didn't read as clearly as a "bought one". Thanks to modern technology, we are able to produce professional quality sheet music in different keys, correctly printed. However, the process is still pretty labour intensive.  To get an exact copy of the music, in the new key requires quite a lot of checking and 'mouse work' from me, all of which takes time and money!    
Now, I am talking of the standard vocal score here- melody line, chords and simple piano accompaniment, the form that most pop songs and song folios from musicals are printed in. Now rather than simply saying to every client that the full transposed sheet music is the only version I will produce here, there are ways of short-circuiting the time required for me to work on the project, and that can save you money!!! There are a few options here:   Before I explain these,  it might be good for you to know just how the transposition process works:  
I use two methods, depending which is faster and therefore cheaper for you.

Method 1. Using some quite expensive software that scans and then tries to transpose the music automatically. The software 'photographs' the original sheet music and then "guesses" what the notes are, and presents it in a way that I can then edit on the computer screen. If you have a look at a piece of sheet music, this is quite a remarkable thing for it to do. The way sheet music is written out is quite complicated.  The computer has to recognize the ledger lines, the bar lines, the individual notes, lyrics, key signatures, all sorts of symbols. It doesn't always do this very well.  So, as part of this process I have to go back and very carefully check every note and every symbol to see that they are okay. The checking of what the computer has 'guessed' and than making the corrections manually is the most time-consuming and therefore expensive part of the process. The software does its best transpose the music the preferred key. It does this instantaneously, BUT once again, every bar has to be checked very carefully by me, because the computer almost NEVER get it right.  It is quite a complicated procedure!! How long the process takes depends a lot on the condition of the original sheet-music. The better the music, the better the computer does the 'guessing',  and then, the less work I have to do to correct it! This is why the results and FEES are unpredictable.

Method 2: I key in each note individually into some other software. That program then does its best to transpose the music. Results are generally more accurate but the keying in process is very time consuming for me. And correction still needs to be done.
Some Cheaper options: Now, I have discovered in practice, that sometimes people do not need a complete actual copy of every single symbol and note on the music.  For instance, you might like to think about whether you really need ALL or ANY of the lyrics printed out on the music.  (This is a quite time-consuming part of the process)  

Some things to think about: If some of this following passage doesn't make sense to you, you may have to consult with the musician you are working with to explain it to you. Feel free to give your accompanying musician / musical director / teacher my contact details and I  can talk with them directly if necessary.  
1. Do you need to have all the chord symbols written down?
(This can be quite time-consuming doing this) Leaving these out would save you $$!
2. Some of you may not need the lyrics printed out in the music.  
(Once again, a quite time-consuming part of the process.)
Leaving these out would save even more $$!

 3. Consider getting me to make a 'chord chart' or 'lead sheet' instead. 
It will take me a lot less time to produce this simplified form of sheet music, and depending on the musician you are working with, this may be all that is needed. (What I mean here is that doing a full piano transcription of every single note in the full sheet music, may not be required, if your musician has the ability to simply work from a melody line and chords)

***However, this may not be appropriate for auditions.  You have to use your discretion here.  If you are doing an audition for a modern rock based musical, it is quite likely that the musician playing for you will be able to play from a chord chart, but you can't always count on it.  To see a detailed explanation of the difference between full printed sheet music, chord charts or lead sheets follow this link:   What is sheet-music?

So in summary, it is the searching and checking of what the computer produces that is time consuming!! - and time is where the cost lies. And frankly, it is also the part I least enjoying doing, so if we can cut it down, we will ALL be happy!

Here is another  interesting option:
    A client recently asked me to simply send me the music exactly as the computer had "guessed it". I had a quick look at it and corrected some of the dreadfully obvious errors.  -Sometimes the poor computer will absolutely and completely stuff it up!   The client took that printout to their accompanist, and together they discovered where all the errors were. They then sent the copy back to me (covered in red markings!) telling me EXACTLY where the errors were.  I was then able to correct them very quickly with minimal cost to the client because I didn't have to do (and be paid for!) all the tedious searching for errors. (If you have the necessary music skills you could do this 'checking' process yourself!)

The client was also able to make the decision that certain errors in the layout could be "lived with" - (There are many small errors in the transposition that occur, that don't really matter, but are quite 'fiddly' and time consuming to change, but the client can make that decision themselves.   Using this process, they were able to basically halve the cost of the job!! That would be nice wouldn't it??? So if you or your musician friend can do a lot of the checking that will save costs too! So, quite a few options here for you to think about..... Contact me for more clarification.