Originally Posted by slawecki
This is usually due to one or two auction pscys coming out.
a. somebody else thinks it is worth more,so I'll bid more or
b. well, I offered x, so I guess I'll try x + $5.
and of course
c. they have no idea the value of the item, either in the real world, or to them.
I usually don't much mind, as there are usually more of the same thing coming down the line, however, this item is serious money by my standards(around $20,000), and I would just a soon not have idiots bumping the bid up for days at a time by $100s.
You left out one not uncommon category: The Shill Bidder. More common than many would expect, especially on big-ticket items. Sniping is your best bet. In fact, unless I'm using Buy It Now, I always snipe. Auction Sentry Deluxe is my tool of choice, mainly because I can create chained lists of items: If I lose A, snipe on B, and so on.