There's a mall in Las Vegas, recently opened, that is made of shipping containers.
And there's a sample building on display just off of Bricktown in OKC
Apparently, shipping containers can only be used a dozen or so times (at sea) before they have to be decommissioned.
I'm looking into them to build a very remote house/cabin in Mongolia. I'm also exploring their use as greenhouses as there's a number of companies having success with them in that area, especially to grow mushrooms or for use with hydroponics.
I can pick up the very largest units 40' or 45' L X 8' W X 9.6' T ("High Cubes") in Mongolia for around $1,500 and brand new for double that. Those interior dimensions you end up with something about 7'6" wide with a ceiling height around 8'6" - put two of them next to each other and you would get about 640 sq ft, three would yield 960 sq ft. But there's so much you can do with them to purpose them in ways and put them together to get a lot more than the sum of the parts.
I'm thinking something like this, with a canopy on top, with a grill/smoker up on the deck would make one hell of a summer cabin. It would only take 3 or 4 containers to form the shell.