I still don't see that its a primer. Good high heat paint is expensive. I don't remember what i have paid for mine but I know it was over $100 a gallon. The fire box is the only place the paint will come off. I just give it a spray of oil when it cools down.
Green UDS (UGD)
Blue UDS (UBD)
Homemade 18"/36" Grillzilla
Lang 60, (RIP)
Home Built Trailer (500gallon Oil drum).(RIP)