Always check feedback. If someone has a negative in the past 6 months, and it's not something stupid (like when sellers give bad feedback to buyers, because the buyer gets angry when the seller cheats them/ships SUPER slow, or whatever, hate that), then I plain out won't buy from them.
I'm terribly picky on ebay, and the worst that's ever happened, was the post office lost an old Eagles record I ordered, and the seller apologized profusely, refunded my money, and shipped me another copy free of charge.
Just gotta know who you're dealing with, really.