For cheap sheet metal look for junk washers and dryers, heck half the time they are tossed out while still working and looking like new also!
I bought a really nice looking and working gas dryer for $10 at a yard sale, like new, they moved here from a big city with a natural gas dryer then couldn't use it so bought a new propane dryer LOL
Anyway I haul them home from scrapyards and elsewhere for about $3 as scrap, then strip them for the motors and other parts, that sheet metal is great for many things! You might want to sand blast the paint off it though for an oven if on the hot side. If your looking at really old ones they may be rusty around the bottoms but I pick out the good ones that have no rust. I buy allot of junk from scrapyards, you haul it in and I haul it home
