I was able to get 2 4x8 sheets of 20g from Nivert steel in WilkesBarre PA. $75 total. The one door panel I have is definitely thinner than 20g. But the door looks to have been 'repaired' before... lots of weld bead where there should be none so its been worked on before.

I have 3 more to fix. The dolly work is quite easy, and I am surprised at how close I can get it with just beating on it. Still need some filler... but not much more than a skim coat.