I wish Radio Shack still carried AV cables for older gen stuff, like they used to, since I'd love to find a stereo Sega Genesis AV cable for a model 2 Genny. I've found one online, but the cheapass in me won't pay over $7-10 shipped for it, so I guess I'm SOL.
Funniest part is, I've asked numerous RS store employees at many of their stores if they could even order it for me. They referred me to Gamestop, who referred me back to them, then another RS store clerk referred me to Gamecrazy.
It seems that NO ONE has these anymore.
Oh and OP, you just need to give them a call and find out which store has what you want. Though, if they don't have what you want, you could possibly order it online, but the shipping costs may kill any deal you might otherwise get.