Good timing for me on this topic. I've looked at a variety of buildings, from pre-engineered (steel) to pole barns to the agricultural metal domed buildings.
Decided to have BCI Barns out of Oklahama build a pole barn as I cannot afford to do slab and metal building at the same time. Doing the pole barn will get me a storage building on site quickly, after which I can do the slab myself as I get time. Slab cost for me to do it will be about $2200.
The barn will be 40x50x12 with painted 26 ga metal exterior panels, rat guard at the bottom sill, walk door on the side wall, skylights, 10x10 sliding door on the back wall and and I will install my own metal roll-up doors on the front wall. Total cost is $11,500 for them to show up and put up the building.
I don't have the time or help available to do it myself, so the solution was to have it built. I usually do this stuff myself, but sometimes there are too many other things to cover. They have been pretty good to work with so far - we'll see how the barn turns out.