Thought I might add a few comments.
I purchased a 40' aluminum container in the mid 80's. Paid $275 for it. The only thing on it that isn't aluminum is the two end caps and the floor. All cross members are also aluminum. Weight of it is just UNDER 3500 pounds.
The cross members on my container are exposed, which is something they changed on most models, due to the damage being excessive. I CANNOT drag mine as was suggested, and pictured due to major damage being done if I do.
Another thing, sitting the container flat on the ground is hard on the wood floor and underside due to the moisture in the soil. Block it at least 8" and build the ramp a little longer, or pile dirt up at the opening. In the long run, you will appreciate the added life of your floor. Mine was doing fine till I moved it and set it down on a unlevel area, allowing one end to touch the ground. That end had the floor rot over time and replacing the floor is more expensive than buying another container. I have considered scrapping mine out and taking the proceeds and buying a cheaper steel one.
If you talk SWMBO into letting you buy one, get the biggest one you can hide in the edge of the woods, and add some paint to it to help hide it. Taking the time to glue insulation foam to the walls might help make it less likely to sweat on the inside, as many do. Keeping it at a constant temperature would prevent that, but they don't usually get that treatment.
Dehumidifier, or exhaust fans will come in handy. Another thing I did was build a small crane rail system in it. A 4" rail and supports that run up each wall, over to the center where the rail was hung were pretty much out of the way, and gave me a way to drag heavy stuff into the container. It would also give you a way to stack implements.
I had mine moved the last time on a Landoll trailer, about 30 miles, for $100. All the other times I moved it myself, using a house jack and a lot of dunage, and an I-beam to hold one end up while I backed under it. A shortened 65' mobile home came in handy as a trailer to move it on, dispite me never unloading it to move it. Heck, one time I had two Corvettes and a lot of spare parts in it while i moved it.
David from jax