$ale of the Century or Temptation:
Let winners buy something in the big sale AND come back the next day.
This would make the end-of-show decision more interesting. They have to win more games for the grand prize--that's the risk--but they're more likely to buy the catamaran if they don't have to pass up everything. Players retain any Temptation Dollars left over, and the host could lower the price or add bonuses to coax them to buy as in the front game. Perhaps farther up the ladder there's a bribe to leave, say $25,000 if the car is $60,000, and once they get to the car (the grand prize), they buy it and leave or risk it to add the lucite briefcase of cash.
One other small thing: Back in the big sale, winners get a refund of what they spent on bargains in the front. You want them to buy to keep the game close, and this removes a reason not to.