Better common? GG is an odd one to talk about better and common because the truth of the matter is outside of a very few select US releases they really don't pop over $15-20, just Mega Man gets $80+ retarded and it's not even an excellent game.
I've got 40 titles and of those I'd say most of them I'd definitely recommend, problem is I don't know your tastes. If you are into Disney stuff there's 3 fantastic platformers in the ...of Illusion line starring Mickey which all just cost a few dollars each. SNK fans can pick Bust-A-Move, Fatal Fury Special and Samurai Shodown which are well made honorable conversions and they're like $10 or less. But if you want to get into the $10 or less cheap but unique stuff less mentioned -- Halley Wars, Magical Puzzle Popils, Pengo, Aerial Assault(personal favorite), Ristar (not the Genesis game), Revenge of Drancon, Wonderboy 3 Dragon's Trap, Devilish, and Dragon Crystal. Over $10 but less than $20 there's a truly fantastic RPG known as Defenders of Oasis that I'd call a must and despite age it has aged well enough not to feel sucky and dated, and only if you like tactical RPGs there is a solid single US release of Shining Force. Vampire (it's like a castlevania knockoff, but really good too) and Psychic World (sorta but not mega man-ish sort of.)
There's the usual 1st party Sonic, Tails, Ecco, Streets of Rage, etc stuff worth a grab too but that's kind of a given.
Here's what I have, you can check reviews out easily online maybe at a place like smspower or something or sega-16.com --
http://tanooki.byethost16.com/segagamegear.html Almost all of those cost me like $3-10, a few were more but nothing was over $20 that's for certain.