It sometimes lacks any sense, though. Years ago, when film equipment still was the norm, i tried to buy the 60 mm Distagon for the 1000 series Hasselblad. As it happens, there were 3 for sale on eBay, auctions ending within days. All in similar good to excellent condition. There was a lot of interest, and bids went up quite high, too high for my liking. So the first went for a lot, with many bidders. The second a few days later, the same. And a few days later still, i got the third for less than a quarter of what the other two went for. Both the seller and me were quite surprised. Where had those people gone, who had missed out on the other two, despite wanting one enough to bid a lot of money? The market often is difficult to understand, because it is not a rational thing.