So, with a bit of googling, I found this awesome website which explains the costs of sprites and commissions for both artists and requesters.
http://2dwillneverdie.com/blog/how-much-do-sprites-cost/
Just thought this would be useful to a lot of people here!
(Sorry this is not a request for art. If this is in the wrong section feel free to move this to the correct part of the forum!)

Edited by Blueberry_pie - 13 June 2013 at 8:22am