OK, so I just thought of this, but I can’t imagine it’s not been thought of before.
A site that sells one item at a time.
The in stock quantity of said item is unknown.
The item starts at a price, and then the price gets lower as time passes–it is based strictly on time, and not how many have been sold.
The fun part for the buyer is waiting long enough to think you are getting a great deal, but not too long to where the item sells out and you miss it.
After item sells out, next item starts.