Sale of the Century
$ale of the Century first aired in 1969. It ran for a big chunk of the 70's, and nearly all of the 1980's, where Jim Perry was the host. The show featured three contestants (in the 80's show), usually one a returning champ, answering questions for cash and prizes.
In this game, each question was worth $5 (or more) for a correct answer, and minus $5 for an incorrect answer. Each player started with $20. At points during the game, the contestant in the lead would be offered the opportunity to buy prizes at deeply discounted prices ($5 or $10). The money would be subtracted from their bank and they actually got to keep the prizes, even if they did not win the overall game. The contestant with the most money at the end of all rounds was the winner and would then be able to buy from a bigger prize package.