They can be supported at the four corners if you want it up off the ground a little.
You can exhaust out the sides - vents low on one side and high on the other, but most are made air tight if you want to keep humidity out. Find a shady area for it and that will keep it from becoming an easy-bake oven and will help with condensation if it's an issue.
If you're just looking for storage, find one with the welded cover over the lock area - it prevents bolt cutters from accessing the lock and makes a pretty secure door.
A string of lights and a couple of receptacles down one side makes it even more versatile.
They are built like tanks and were made to take weather and abuse, but there are many on the market that are in bad shape - plywood on floor can be torn up, can have lots of rust, and leaks...be picky and get one in good shape.
They used to be cheap, price here averages $3 - $3,500 for a good one.
Another option is to get two, set them apart 10 - 20' and get 10 pre-engineered wood trusses to cover both the containers and the space in between. It keeps the weather off the top of the container and gives you covered 'garage' space in between.
There are unlimited things you can do with them. I was going to use 8 and make a cabin, but the cost to purchase a good one now made that not really feasible.
