I've been doing copper cookware. Can pick up a dented pan with bad lining for $5-$20.
It was a learning curve but with experience in autobody it wasn't to hard to learn to fix the dents.
Re-tinning I'm still not great at but can get it down. I see video's of guys doing it it 3-4 minutes.....takes me 3-4 hours! That's where the money is. Retinning costs $5-$6/inch. [Base+(2x)hieght] So a 10" pan with a 2" hieght can be $70+. And they charge shipping, each way, at $15 minimum. Figure $20 cost, $70 retin, $30 shipping.....not much room for profit. Do it yourself? About a buck in tin, a buck or two in propane and couple bucks in supplies.
I've sold pans in for hundreds.
Took a while to figure out what pans are good. Got burned on some. Now I can pretty much pick up a pan and tell from color, weight and design where it was made without having to examine it. But I'm still learning. I picked one just last week that I thought was good. Paid $10 and it's selling for $20. Only good thing is it has a lid. I can swap it over to another pot and raise the price. People will pay a lot more for pots with lids even if its not a matching one.....