I've got yet another theory for why they would. Maybe they're priceline people who get the 10 ebay anything dollars for every transaction. So maybe this transaction isn't costing them that much at all. If I had anything points (alot of them), I might use them to buy hotel gc's as well......because they wouldn't be costing me as much as if I went to the front desk and paid.

The seller could have also gotten the gc's at points.com so they were basically free for him. So any amount is a profit. He's just lucky it was a demanded item.

BTW, it is not illegal to sell gift certificates. Even ebay has a category for them. You just can't sell miles (although some sellers do) or reward nights.