Right now the Housing buy system is reduced to spamming a placard for HOURS... I can't call that a very good system. Why not just make a Randomized Queue system where everyone that comes to a placard for sale gets put in a random pot and gets drawn at random?
If a player is selected to buy they have 280 seconds or something to make the buy or else it goes to another random draw.

I may just over-simplifying things but this seems like a much better idea to me than what we have...