I am currently working on several sets of stock game art - so far mainly characters. Check out the BlockBuddies: BlockBuddies game art
Each set comes with 53 frames and 4 sizes (S 64x64, M 96x96, L 128x128 and XL 256x256) and also includes a flipped version for game engines like GameSalad.
The sets sell at USD 15.00 with the bundles containing 3 characters selling at USD 37.50 and two character sets going for USD 20.00.
[This is a sample of the frames - and the dummy is free to use in your game (commercial or free).]
Chris 2dgameartforprogrammers blog