The 15x7 Fenton Gyro racing wheels are common and not too pricey but the 15x 3 1/2 and 4 inch are high as well as the 15x8 1/2 wheels. I sold a nice pair of U.S.Indy brand 15x4 1/2 wheels recently for 400 bucks and the guy almost broke my hand handing me the money... I grabbed a NOS set (4) of Ansen sprints in the original boxes from Gardena,CA for around a 100 bucks but they were 14x7's...
I think I have 300 dollars in these Fentons. 15X3 1/2 and 15x7's. It seems to vary quite a bit, especially if they have been polished or not...
Tommy