Last time I checked Earthbound wasn't too bad of a price on ebay, but last time I checked MIGHT have been ten years ago SOOO.
I'll give you some of my faves that might be less likely to be named by everyone else.
Illusion of Gaia. Classic, classic action adventure a la Zelda
Lufia 2: Rise of The Sinistrals. Might be a tough find. Great rpg with some fantastic, fantastic puzzle solving.
Donkey Kong Country 2. Don't listen to the haters, the series wasn't all style and no substance. This game in particular is the highpoint to the series.
Zombies Ate My Neighbors. Classic action game. You run around shooting zombies and aliens and vampires and giant fucking babies. It's also co-op, and super hard. So if that flips your switch...
Mario World! Castlevania 4! Super metroid! Earthbound! (Seriously, find yoself a copy).