I'd be a little leary of Ebay equipment. You never know what the previous owner did to the gear and you never know what UPS is going to do to it during the shipping. I've never bought used audio gear for this reason.
I've purchased audio equipment from eBay and have had no problems... just bid on auctions from sellers who have good ratings... that's what I do. I only bid on audio equipment that is new and not used.
Just remember that most of the solid brand name manufacturers do not allow their products to be sold on line. Many go as far as to void all warrantees on on-line purchased equipment. You have to ask yourself if having to pay for repairs on something yourself is worth the money saved now. It may cost you lots more in the long run.
I've never had any problems with purchasing off ebay. As far as electronics go, I don't really buy used (although my phones are used from e-bay and work great). Everything else is new, so I don't have issues there. If there is an issue, its a warranty issue. But, thank god, that hasn't happened.
I've bought most of my things off ebay, but I definitely have to say try to stay away from used or refurbished, and try to go with the "stores" they usually have several hundred to several thousand on their feedbacks. Just be careful, and have fun, thats the best advice, and like when buying from a store as well, shop around, and study study study. I've been screwed more by the local audio shop than I ever thought about being screwed on Ebay
I've bought many things off ebay and never had a real prob other than slow shipping on one. My friend buys a LOT of her stuff from ebay and loves it. She even bought her 94 Mustang GT off of there and absolutly loves her car. just be cautious and it should be good.