Grand Game's top prize is actually still a little above average if you factored all non-car games at this time, although keep in mind, the GP setups back in the '80s were tougher than they are today, with multiple tricks like family-size packaging and multiple items that hug the Target Price. Its not like these don't exist nowadays, but GG was won less on average compared to recent years.
Or increasing the bonus for ordering the groceries correctly in Hole In One, which actually has been awarded less often than it already has been, as rarely as its given away. If it's won only once a season on average, I'd add a 2 at the beginning of that gold flag, with an extra 0 to that flag at the end for primetime. Its beyond overdue for an increase since a similar retired game played back in the mid-80s using various skilled offered a bonus for twice that amount, and it was easier to win. But at least up the bonus to $1000 even if that's still worth far less than what $500 bought in 1977. Think about how much a movie ticket cost to see the first Star Wars movie (released the same month as Hole In One) as well as one from the sequel trilogy.
Even the Card Game is soon to be due for a higher opening bid with the last two cars offered around $9-$10K above it, despite the easier ranges to zero in on the price.
Since the main goal of the SCSD is to simply get into the Showcase anyways, and getting a dollar usually means that you will make it over there, barring an unlikely Spinoff/Bonus combo. The real money in the SCSD comes from the Bonus Spin, and the higher payouts there make it exciting to watch even if the spinner has already secured a spot in the Showcase at that point.