Note that there is also only 1 copy on Amazon. I went through this when I was trying to purchase this adventure. It took me months to win a copy and my bidding tactics earned me some unkind messages from other bidders (saying I was driving prices up too quickly), but I never wanted to go above $45 for it. I eventually got mine for $42, but there were some "dry spells" during that chase when it was going for oscene amounts of money, since there was only a single copy for sale and some time before and after when there were none available.
As has been said, this is great for sellers, as I am occasionally. Sometimes I list similar items and sell them for wildly different amounts of money. Sometimes something doesn't sell, then goes for a good bit. Such is Ebay.
DM