Leaded gas verses unleaded is cheaper?

Leaded gas verses unleaded is cheaper?
We no longer use leaded gasoline. We only use unleaded, which is sold in three octane ratings. I think it goes Regular unleaded 87 octane, unleaded octane 92, then maybe 97 which they call premium. Lots of people buy the middle or higher grade which costs more, and doesnt help any ! If you car runs ok on regular there is no use spending the extra money for the middle grade. In fact there is so little difference they should come from the same tank. Check your owners manual if your manual doesnt tell you to use premium, then use the regular which will cost you less.