Toyota Man,
First off, there are no dumb questions. You are correcton the huge difference in prices on some of the Slot It cars. Some of the older cars are now collectors items and are listed on Ebay and other retailers for huge sums of money while some of the more recent releases are below the suggested retail price. The best bet is to look for one of these newer ones like the Porsche 962KH in the Jagermeister colors. You can also get a new Porsche 956KH in the Gulf livery. Both cars can be found for $50. You could also get a Toyota 88c if something like that sounded good to you.
All of them are mechanically the same with a different chassis for the different body styles. This makes it easier to swap parts between cars if needed.
Marty