Leaded gas is very hard on some of those wideband O2 sensors. They probably won't last quite as long with heavy leaded gas use, but if you want to go fast then you get used to replacing parts like that and clutches and trannies.
I will try to get some prices on Monday. The prices have gone up over the last coupel years, but it's mostly been due to transportation costs due to rising diesel fuel prices. It costs a bit more to get C16 up here than it does in Texas.
