There are 2 metal suppliers in town- Westbrook, and Metals4U. Actually, both are now owned by the same company, but they’re managed differently.
Both price uncut metals similarly according to market. Protip: to browse prices, go to https://www.onlinemetals.com/ because they follow market prices too. Westbrook and Metals4U prices will be in that ballpark.
Their cutting policies for less than full-length stock are different between the 2 shops, it does change the price, but not by much for linear stock at least. Plate can be a different matter. You will need to call ahead to get stock custom cut, and they may give you an availability date a day or two later.
There are 3 categories- there’s full uncut stock, there’s “cut stock” of the remainders after someone buys part of it (only slightly cheaper, avoids like a $5 cut fee) and at least Metals4U has every piece of that on computer to tell you what’s available in exactly what length. There is also a scrap area where you can pick up smaller remnant pieces quite cheap of various profiles of steel, aluminum, stainless, and copper.
Fair warning- Metals4U parking lot is HELL during their busy hours. It is small, an awkward “L” shape, often blocked with huge trucks, and there is often obstructions of metal shipments laid out on the lot, sometimes very low and difficult to see in your mirrors. You cannot park on the street, as that is I35’s access road. But Westbrook is a straight shot to drive up to.