If there is a track nearby, go out some Saturday night, get a pit pass, wander around and check out the track tires. Most tracks have 1-3 entry level classes mandating d.o.t. tires of various sizes. Most also have 2-3 mid-upper level classes running on racing slicks. Most tracks also have 1-2 modified classes running psuedo open wheel cars, some allowing slicks, some required treaded tires.

IMCA sanctioned modifieds seems to be the most popular in the middle US. They require the American Racer L60, on dirt and asphalt, which is treaded tire about a 275/60 with square shoulders and soft compounds mounted on a 15x8 rim of various offsets depending on position. I think this rule set and approach has also been adopted by Cascar and other non-sanctioned tracks as well. The breadth of its usage is one means of keeping prices down.

Oval track prices are cheap because everything is a consumable there, from tires to entire cars. Of course, 99.5% of them are all rule regulated chevys as well, so commonality helps drive prices as well. In my neighborhood there are the occasional Ford and Mopar drivers, but I'd imagine most places are not too dissimilar.