What I'd really like is a hangar with some vault/storage space nearby, so the hangar can be reconfigured for various projects (with tools/etc. on roller carts to a great degree, or in side partition areas with roller doors so they can be opened up to the main hangar space).
Steel span structures are fairly cheap, but I suspect I could buy an old factory (ideally something fairly clean) for less than construction cost somewhere. A shotcrete shell with steel mesh would be fine too.
My ideal home is something that is less than 10% of my net worth.