I've seen sellers on amibay increase their item price over time, I don't think there's a rule which states you can only decrease it.
The first in line rule is a good thing. Imagine this.... a super rich Amiga hater who buys everything that's ever for sale on amibay and then destroys it. He creates mass bonfires of Amiga computers and related gear and films them as they burn, after which uploading the videos to youtube.