A res auction would be the sale of a lot that has been un-active for 30 days. There would be a pre-set price, depending on the things built of the lot. (Empty lots would start at 100R, lets say.) The buyer gets everything on the lot. If the lot is not sold, it is reset and put out for new players. Any player can buy, but since the prices might get very high, your outcome is based on the rupees you have, making member ship a easier way to get more lots.