Well I don't know about "cheap", compared to what?
Goodyear Bill Board, or sometimes called Cobra, tires available from Shelby and a few other limited sources, are generally about $200 per tire. Price and availability seem to vary quite a lot though. Compared to Avon radials, which the Kirkhams seem to favor, they are "cheap". I think the Avon's run about $400 per tire or so.
Looks like one set of your wheels/tires have Hoosiers? I don't know anything about them, interesting choice. One thing for sure, DO NOT skimp on the tires, traction should be your first priority. You see some really nice high dollar rides with $1.98 Goodrich TA's on them, that always leaves me baffled. Like wearing a tuxedo with tennis shoes.