I buy on ebay a lot and sell quite a bit as well. If I really, really want something, and especially if the auction ends when I'll be at work or away from the computer for some reason (imagine that!
), I use esnipe. Their computers will place your max bid 6 seconds before the auction ends automatically. If you didn't bid enough, you lose, but if you bid the most and no one else knows your bid, you win -- so I win most of the auctions I "esnipe". It may sound a little unethical, but believe me, this type of bidding goes on ALL THE TIME on ebay. There are several different auction sniping services, esnipe is only one. You do have to pay a small amount for "esnipe bucks" (using Paypal), but when you first sign up you get a certain number for free, and I just put $5 for more bucks in ever so often, and it lasts a long time.
Just wanted to let you know that this exists. It's MUCH MUCH less stressful than hoping your internet connection won't die with 5 seconds to go in an auction, staying up all night until the end of an auction, or risking getting fired from your job for being on ebay at work! 
Emily
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow