I 2nd Des Moines Steel for buying new steel. They have reasonable prices and they do free cuts. As far as cheaper options, try calling or texting Keegan at
(515) 779-3985 and see if he is still selling used steel.
Another for scrap steel and lots of other surplus items is Ott Equipment Co in Ankeny. There address is 1157 SW Ordnance Rd, Ankeny, IA 50023. That is an interesting place that I would be more than happy to give you an introduction and a short tour.
I also have several I-beams and round tubing that I might be able to sell at a reasonable price. I left a small sample of one over by the lathe at the space. I have several of those that are a little over 8' long.
What type of steel are you looking for and how long of pieces? I know a few other guys that have lots of steel and might be able to help.
Ryan