>>2683841
If you permit it first you can build a garage in usable stages because I did. I used a Steelmaster shell bolted to steeI I-beam (the beam was a little narrower than the Steelmaster base channel so I notched that instead of drilling and used wide washers).
When I moved I unbolted the shell (I anti-seized all the fasteners and only had to cut three) then when I set that up I welded two steel pipe verticals to the bottom of the side beams (20-footers but length doesn't matter since beams can be sectioned). Then I placed the verticals in holes dug with a posthole digger and potted them in concrete. That supported the shell which was immediately usable.
When time came to pour the slab I closed the ends of the beam base with other beams forming a box then poured the slab. No need to buy wooden forms and I can and did weld and bolt what I like to the outside of my steel-encased slab.
You can order steel building kits and panels as your wallet allows, for example doing half your final size, putting that to work, then when you have money get the second half, then get material for however you want the ends.
Steelmaster (and clones, they're all descendants of Wonder Arch) also have container roof kits so your walls can be shipping containers (buy only one-trip grade, no condemned junkers) for gasketed storage and instantly usable space. My 40' High Cubes are separate from the shell which better suited my use case but if I add more I'll do a roof kit too.