Are you looking for pre-made pics, like official art, backcards, etc? Or are you looking for an artist to draw you something specific?
If you're looking for custom art, you can check out the
Commissions Artist Thread or see if you get any nibbles here. For something specific like that, you're looking at art that you will either have to pay for or trade for, depending on the artist. But we have some very talented ponies who are open for commissions right now.
If you're looking for something a little less specific, you might just stalk adoptables for a while. Once the weather starts to turn, the autumn-themed adopts should start popping up.