I have small spots of rust starting to form at the bottom of my rocker panels from rocks I assume, and i was wondering if anyone has any experience's with applying Rhino lining or Line X or any other type of lining in that area. If you do could you please tell me how yours turned out and how much it cost

 

I sprayed my rockers, to the trim line, and around the fender wells, with color matching armaguard, it looks great, and by the time the metal rusts away, youll never notice caus the aramaguard would still be intact, its heavy duty, will post some pics for ya.

 

Mine are further along. Lots of rot showing through on the pieces not already repaired. Next step is going to be slicing them off with a cutoff wheel and welding on patch panels.
I suppose if you bought pre-made rocker panels from somewhere online you could paint them with zinc primer and get more life out of them. Drill drainage holes first though.
If you want to make them last a bit longer before repair, try buying some metal-ready from POR-15 and spray a bunch of it inside via the body plugs under the truck.