Problem with the Costco tarp sheds is they don't last very long. And the cover to re cover them is almost as much as the original cost. I don't know what you are wanting to do but the other concern is security. Those tents are very easy to get into. They also sweat like crazy so anything stored in them needs to be sealed to the weather. Anything cast iron like a table saw or lathe or mill is going to need ongoing care not to turn into a ball of rust.

I have a small tent shed that 8x10 and the cover only lasted 3yrs and it was going to be $200 for a new cover. I ended up skinning the bare frame with corrugated metal from Home Dump for less than the cover costs and it will last who knows how long? I don't try to work out of mine because it's too much of a headache because of the very silly tent doors besides the previous reasons. By far the best solution is a container like MeJasonT mentioned. Most places you don't need any permits because it's temporary. And because of the slowdown of trade w/China there is a glut of containers and prices keep slipping. They are not perfect and more than you probably want to spend but they are sturdy, secure, already have a floor, pretty bulletproof and you can take them with you.