I decided about a year ago to sell some art. Either traditional art (charcoal portraits) and graphic design work. My prices are very fair. starting price at $10 for a 8.5 in. x 11 in. + $10 for each additional face. I only do 2 faces on a 8.5 in. x 11 in. because if I do more, each individual face will be smaller, and I feel it will looked squished. Another size that I offer is 11 in. x 14 in. Starting price for that is $40 +$10 for each individual face. So example; if you want 5 people on that size, the price will be $80. I haven't started charging on time, but if it is an animal portrait or nature portrait. I might charge with different prices. I know for sure when it comes to animals the starting price will be $40, but I will most likely charge an additional $20 for time... hair is not easy to do, especially if it's all over the body.
When it comes to graphic design. Starting price usually has been $30. But usually that is for wallpapers/logos/banners. If it's something very elaborate the price will go up.
For more information, please go to my Facebook Art Page at www.facebook.com/ArtsyCubenerd.