It could be a bidders-sellers group. They would arrange to bid-up an auction, then the seller pays for the final bid. They would take turns bidding up each other's auctions.
But the seller, in paying to process the buy, would lose the percentage that eBay and PayPal take out.
However, it might bring in some suckers, because the next time a similar auction from the same person starts to go up, the fake bidders stop short enough to make it look like a steal, and someone pops a relatively low bid at the last minute, like "only" $600.00. And that is a steal, just not the way the buyer thinks.
Other than that, I have no idea why those would sell for that much.