I've considered buying SSD's on ebay, because I have a really tight budget.
I've followed SSD developments and I've noticed that lots of brands have really bad feedback on newegg.com. I would be scared to buy one of these new from a good retailer with a good return policy, much less buying an old used one from a random person on ebay. I decided that Intel and possibly Crucial had some models with good track records and if I was going to buy on ebay I would limit my search to one of these. Following auctions for awhile I found some sellers that semed reasonable with their return policy and had good feedback, but the final selling prices weren't all that good compared to the best retail prices I could find so I have held off. For my first upgrade I was interested in an 80GB Intel. I've since decided that I could make do with a 64GB and I've found that I can buy a new Crucial from newegg for significantly less than what the used 80GB Intels sell for on ebay. I've been doing ebay for a long time and although you can get some good savings on ebay, sometimes you are better off to just buy new.