Where to buy sheet metal?

I should have mentioned that I checked Home Depot and they only had the sheet metal for roofing ("R-Panel" not flat and galvanized). I asked two different people just to be sure.
 
Well i havent actually bought from HD, but I've bought some from menards in pretty well sized sheets. I forget what gauge and size, it was for the floor of a go cart me and a buddy built from scratch.
 
You'll spend 4 times the amount at a DIY store as you would at a metal yard. A buddy of mine just bought a piece of 16 ga. steel in a 48x18 or 24 piece for 9 bucks cut. A 12x18 piece goes for about $18 at the DIY. Most sheet metal at a sheet metal shop is going to be hot rolled galvanized which tends to be pretty springy.
 
Current metal yard pricing:
20Ga. (0.036) CRS 40 x 48 = $8.79
18Ga. (0.048) CRS 40 x 48 = $11.74

We don’t buy 19Ga. (it’s also not as popluar).

I disagree with the: “Most sheet metal at a sheet metal shop is going to be hot rolled galvanized” statement. Most sheet metal shops I work with use standard commercial grade SAE 1008 Cold Rolled Steel.
 
Most all the sheet metal shops around here are HVAC, which about everyone uses galv. steel. Same for sign shops, they get some sort of paintable galv. steel or they use vinegar solution to help adhere the paint. This is when they're not using aluminum. Maybe sheet metal shops do different things in your part of the country. I've got a guy in my office that worked for a HVAC contractor and he said they hardly ever had any non galv. sheetmetal in their shop. I had a room mate that worked in a sheet metal shop and all the steel he had was galv. as well. He also did copper roofing and some aluminum sign work as well. What do the sheet metal shops that you work with do?
 
Funny, I was going to say the sheet metal companies you're referring to must be big in HVAC. There aren't many (don't know of any actually) HVAC companies around here; mostly Military (they use lots of stainless and aluminum) and lots of Commercial/Industrial electro-mechanical painted steel enclosures. I guess the type of metal that is most common varies by geography. Of all the products I've designed over the past 25 years (dang I'm gettin old) I hardly ever use galvanized. Primarly due to welding it burns the coating off, defeating the purpose of using galvanized steel. (Plus the toxic fumes emitted when welding).
 
Yeah, no welding here, all pittsburg seamed or screwed I think. Heavier stuff like 16ga. or 14ga. is welded, but I don't tend to call that sheet metal, sorta light plate, LOL!! Equipment cabinets and stuff like that at some of the industrial shops, it's all powder coated, but even these guys, if they get something light gage, it tends to be galv. or stainless.
 
At my current employer most of the 16, 14, and 12Ga. steel and stainless is used on light fixture housings for aircraft carriers and penitentiaries.

For those who don’t have access to industrial forming machinery, I’d recommend using 20 Ga. (0.036) C.R.S.