I found some for sale at my state fair claimed never to warp. But it was over $100 for a SMALL baking sheet!  I’m gonna need a demonstration at least that it doesn’t warp, not just assurance… and even then, whoa 
I bet there are great options for cheaper 

 I'm thinking of trying the USA Pan ones. They are fluted and made in the states. I'm not sure though about the coating they put on the steel. Have you tried them already? 

 I have not, but if they’re coated it’s not really what I’m looking for. 

 Ideally, I want ones I can scrub with steel wool if I need to. They're coated and the cleaning directions make them sound delicate. So now, after researching a bit today, I'm back at square one.