So a large house that is by minimum 45M, you will only receive back 9M gil. A 100M bid would return only 20M.
What is this system design technique called ? It's not even a gil sink.

The result is the rich will buy out all the small houses and then transfer to large if they can. If they can't, then to medium. If not medium, well all small houses are gone.
So, no. This is a bad system.