What is the cheapest way to put up a machine shed?

I put up a lean to made out of some junk steel and narrow gage rr iron. It took a bit of time welding up tabs and hangers but the only cost was the roof metal and 2x4 that roof is attached to.
Has only 3 walls at this time because it is just used to keep rain and snow off equipment.

Then there are fabric hoop buildings, which have come a long ways from even 5 years ago. These are cheaper, but of course, just how long does that fabric last?

I'm kinda eyeing the American Steel for a slightly larger machine shed, but still just thinking. Just offering you some other ideas for discussion.

Of late I see pole buildings built with 3 individual 2x6s nailed together for the posts, only the bottom parts to 2-6 feet above ground are presure treated. They are lapped together with various lenghts of 2x6. Possibly cheaper than whole 6x6 posts. Locally pole barns are getting a bad name, our soil rots the posts off at the ground. Oh, some people use old telephone poles, they might be free. If you have access to low-cost blocks or cement pouring source, you can make a 2-4 foot high foundation & set a 10-12' building on it, sometimes that is cheaper than the long beams of a tall pole shed and no rotting. You were asking for cheaper ideas... ;)

--->Paul