Hi there, I know looking for online mastering can be a minefield. There are a lot of websites that do not show their studio or equipment and just list their equipment (why not show it in a picture if you have it, I say ?) So when you are looking for the cost effective mastering services keep your eye out for those who have a real clients list, show their kit and studio on the website and have a real background in professional audio engineering. This will keep you on the right path to getting a proper job done instead of getting skanked by a bedroom engineer, part timer, side liner or engineering college student. Incidentally one of the most critical bits of equipment (as well as the engineers ears of course) is the right reference grade monitors. I am using PMC IB1S myself here is a pic, full range, large scale, high power, accurate speakers designed for professional audio work :
You can see these are built for the job of mastering audio to a high standard.
Example rates (correct as of 030712) :
1 Track mastered and delivered online £28.00
2 Tracks mastered and delivered online £50.00
4 Track EP mastered and delivered online £85.00
Stem Mastering £40.00 per track.
Album up to 15 tracks £210.00
Master CD-R or DDP - £26.35 / £30.00 respectively
Why not visit this page which gives you a lot of information about audio mastering, whether you are looking for mastering or not it is a good read.
All the best with your music making activities.
Barry - SafeandSound Mastering