The vast majority of third party NES games can be had for under $20. Some of the ones I like are: Rock N Ball, RC Pro Am, Tetris (technically this is Nintendo developed), Cobra Triangle, Snake Rattle n roll, Battletoads, Blades of Steel, Ninja Gaiden 1 and 2, Duck Tales, Jackal, Super Off Road, Indy Heat.. That is just a small sampling, I could go on if you want