Yes, many don't know that Adlo (NJSB) buys steel in 15,000 pound lots. He has it rolled into several sizes, and saws it into several widths. That 15,000 pounds may get sold out in a month. The most common sizes are often sold out in weeks. Look at other widths and thicknesses to see if there is another that will work for you. Also, when it says, OUT OF STOCK, call Aldo. He may have some in the back he hasn't cut up yet or a few bars leaning against the wall.
About 15 years ago, I recall standing around with Aldo in the dark and cold up at Bill Morans when he was just tagging along with a friend. He asked "Where do you guys buy your steel?" We told him there were few sources and the alloys we wanted were slim picking. He said, "Hell, I might as well go into the steel business. Plumbing fixtures hasn't made me rich." After a few starts and stops, NJSB was born.