i think that this is a great idea, however it would call for a change in the forum this is how i think it could and should be used
1. Bump Button can only be used in buy/sell forum
2. Only Thread Creator can use bump button
3. the creator should be limited to a specific amount of bumps per day, lets say two bumps, that way more than likely their thread will remain on the current page of the buy sell forum
just my 2cents though.