Watch the commercial auction sights and local scrap yards if you are looking for steel beams. I got the steel for my last shop at maryland recyclers, paid scrap price at the time + 10 %. Got a 30 foot 8 inch I beam and two 12 foot 8 inch beams for under $500 delivered to my house. Made it posable to create a clear span interrior, nothing in the way. Also, run the biggest electrical service you can, that way you won't be limited to smaller compressors and welders. Also, don't skimp on the lighting, go HID! I put flourecent fixtures in only to replace them with HID a year later, had to rewire everything. The HID's light the place up ten times brighter. And BTW, paint the walls ceilings and floor as close to white as you can, better for lighting. Another thought, put pull pots in the floor when you do the original pour. use 36" X 8" sonotubes with 1/2" rebar and 1' shanks. This was another after thought that was a pain in the butt, and a real mess to install after I monved in. But they make body and frame repairs a whole lot easier.