auctions will always be more of a gamble than buying from a collector, but that is also where you will most likely get a better deal. just ask lots of questions, if the game is close see if you can personally inspect it. if it's to far, get as many high quality pics as possible. if the seller starts to act funny when you request these....move on.
if your friend is willing to spend the $'s then try to find a collector selling one. you will pay more, but will most likely get a game that will give you less trouble, although that isn't guaranteed but your chances are better.
arcade auctions like super auctions are kinda a crapshoot. you will get to see the games and play them to access their condition, but your time is limited and you can rarely find the seller to ask any questions. prices are also all over the board,