It takes a certain mix of desperation, bravery, and cunning to make e-bay work for you instead of against you. There are a lot of idiots out there, both sellers and buyers.
I have bought 2 laptops through e-bay. One from a company and one from an individual. Both are excellent, like-new older machines that I got for next to nothing. I've also bought many computer parts via e-bay for a small fraction of their retail price. Like a brand-new 3Com PCMCIA NIC for $7, brand-new 3Com 56k PCMCIA modem for $15, etc.
But you have to be careful, and if the item description is not perfectly clear, e-mail the seller to answer your questions BEFORE you bid. And be sure to get clear photos of the ACTUAL item, not a similar item or a mfg.'s photo. If the seller has over 100 positive ratings (with no or just a few negatives) I personally would not worry, but it's a judgement call on your part no matter what. For an item that costs more than you can afford to lose, I would insist on escrow. E-bay does sort of protect you against fraud (with a $25 deductible, I beleive), and if you pay using PayPal or BidPay they also offer similar protection.
From what I've seen, current-generation gear (i.e., like what you are looking for) ends up costing about what you would pay if you just went out and bought the thing at the store. Plus the whole bidding thing can be a pain in the rear end. If you are not there during the last few minutes of the auction, some jerk-off is likely to snipe you and win the auction by maybe a penny. It can happen like this: you are the current high bidder, and the current bid amount is $100.00. Your maximum proxy bid amount is $105.00. There's 30 seconds left in the auction, and a sniper comes through and bids $105.00. You are still high bidder because your proxy bid was in first. But then the sniper puts in a last-second bid of $105.01, and he wins the auction and pays $105.01, and you lose by 1 cent, and want to go on a killing spree. I would argue that sniping is the only way to get decent deals on e-bay. I guess all is fair in love and war (and bidding).