Prior to two years ago, 90% of my card purchases were through eBay, with the other 10% being from private deals. Now that I've been dabbling a bit with online auction houses (eg. REA, Love of the Game), it's been interesting to see the differences in bidding psychology between a fixed time ending format like eBay, and a live auction format like we see from AH sites.
With eBay, it's all about the snipe. You bring your best bid, input it to register a few seconds before ending time, cross your fingers, and pray you win the card (but hope you're not overpaying).
With auction houses and the extended bidding format, I can see how things can get more competitive. Sometimes it's best to place a high bid very early, to occupy that top bidding slot which would force the next bid increment to overpay. Other times it might be better to wait until 4am to get in that last bid while some other poor sucker is drooling on his keyboard because he couldn't stay awake.
The bid increments with auction house auctions also play a big role compared to eBay auctions. The smaller bid increments on eBay allow you to fine tune a bid, sometimes down to the penny. With auction houses, however, once bidding on an item gets up into the higher levels, the larger bid increments can cause an item's price to increase significantly with each bid (plus BP).
With eBay, once an item has ended, that's it -- you either won or lost. But with the auction house format of extended bidding, all it takes is one more bid within that 15 minute time frame, and the item
could still be yours. The auction isn't over until you say it's over, and sometimes that can be a dangerous (and costly) thing.