I am also taking commissions for custom sprites.
Sprites for sale:
Small Leafeon $3
Sprites start at $5, prices are based entirely on size. :) It's easier for me to give specific quotes than to try and lay out all possible prices, so just tell me what pokemon you want (and link to a specific sprite if you already have one in mind) and I'll let you know how much it is. If you don't have a specific sprite in mind I can find one for you, of course.
Shipping starts at $1.50, but may be more for larger sprites.
Edit: If you're looking for smaller/more affordable sprites, I recommend Mystery Dungeon sprites, which tend to be smaller than the main game sprites, and thus cheaper, and come in a variety of poses. http://www.spriters-resource.com/ds/pkm
Taking 4 slots:
1. Omastar - Kabutops, Omastar, Cacnea
2. feraligroggles - Feraligatr
3. safetyscizors - scizor, slowking, dragonite
4. sasami - kingdra