Well, just brainstorming here: I was thinking about something like an an auction house where a player enters his/her house for sale and players can bid for the houses. The starting price of the house is capped so players can't start selling their houses at ridiculously high prices. Once the house is sold, only then will it be relinquished and automatically transferred to the purchaser. If a player gets booted however (due to inactivity), the property will appear on the aetheryte as usual.

Example:
I own a 4th class cottage I bought for 4 mil. If I auction it, the price would start at 1 mil and players can bid on it. Since the property is "up in the air", players wont pay for relinquishment, as there is a risk that someone else will outbid him (hence why you can't have a max amount which resulting in the property being automatically sold.)