i bought mine from a pawnshop a few years ago for 100 when they were blowing out stuff. (120gb hd controlers etc) never had a problem with it.
check a few out, you'll be surprised what you can get for next to nothing.
be aware, pawn shops pay the guy 1/4 what it's worth when they sell it. you can grind down the price you see no problem. hum and haw about it. ask if he will take 1/2 the sticker price. if he flat out refuses, play the "get it off your shelf" game. (You make some money, i save some money...) play the "just the system" thing. that will give him some cables and a controller he can sell. i'd be surprised if you couldn't walk out with one.