I'd prefer the purchase system changed altogether.
Instead of random rolls on who gets it, put it on a queue/waiting list.

Basically, allow me to select a Plot and put down the Gil to purchase that plot.
You then go onto a Waiting List and given your queue number.
When that PLot becomes available, the system checks the List to see who is at the top, and grants ownership of the Plot to that person.

You could specify a Ward to try and get a specific Plot, or alternatively leave the Ward blank to have the system grant you the selected Plot the next time a new Ward opens up, or becomes available in any Ward.
Make the waiting list semi public, with a Message indicating how many players are currently waiting to purchase that particular plot, but not revealing player names.

Would make reselling to a specific individual much harder, thus reducing the number of plots that are purchased specifically for resell profits.
Housing should not be a 'player market'. If you have the Gil and the desire to own a house, you deserve to own a house.