Class A storage shelter, barn or garage.

Checking online you will find several manufacturers that make metal buildings and metal roof structures. Once you find the building that you want, then you find a local contractor do handle the concrete slab and building erection. Most building manufacturers also have a list of contractors that they have worked with. I've done several of the metal warehouses and they are just like a big erector set. They are not that complicated but you do need a contractor that can follow blueprints EXACTLY because the building parts are pre-cut and cannot be easily modified.
The slab must be level and must have a vapor barrier underneath it. Insulation would be nice but in your climate it is not that important. The building must be well ventilated.