What would recommended value be? Sorry im just seeing these replies i kinda just picked random numbers i thought should be close for price...
If you want to really to see how artists are pricing their works you should spend some time on DeviantArt.
Many very good artists are accepting commissions there. Browse DeviantArt find someone with similar style to yours and you will see how much people are willing to pay.
For know I don't think you should sell your drawings, spend some more time to polish your style. Good luck.