It varies per org and depends on earlybird pricing, but Blackhawk farms northern Illinois is about 160, Road America about 250.
Now this for the win: USAIR kart track, Shawano, Wi: $45 to rip all day, with no CR's to suck the fun out of your day. 18 turns and 1.1 miles of technical prime asphalt with traction forever. Hell yeah.