For raw steel, I go to the metal mart in Amarillo because it's the cheapest place to buy square tubing here. I had an order in for some 20ft sticks of 2inx2inx14gauge gauge and the truck was running late so they gave me 24ft sticks of 10 gauge at the price of the 20ft 14 gauge.
For metal building supplies I go to Muller because the GM of the one up here is on the Counsel of KofC with me.