Why did the "you" character bid $99, or $49 over what the earlier person had bid?

Was it because he was a moron, and thus deserved to pay the moron tax?

Was it because he really, really, really wanted that part and felt $99 was a worthwhile bid in order to ensure its purchase?

Was it because he understood the item to really be worth $125 but thought he might get it for less?

The correct winning bid was $100 by the shill or flake bidder. If he chooses not to pay that price, there's no guarantee anyone would agree to pay what they bid on the item. Of course, the other bidders only bid what they thought the item was worth, right? So if they were approached with a second chance buy offer, they'd take it since it would be in agreement with what they thought the item was worth, right? You don't think those other bidders would be sucked into some insane bidding war by shills, do you? Who would be that stupid?

That's really what you are complaining about, isn't it? That people would allow themselves to be dragged into some insane bidding war caused by shills and they'd bid way too much for something, not get it, then be asked later if they'd want to buy it for the price they bid. Then it's not their fault and they shouldn't be held to blame.