There are lots of threads and reasons why. But please, don't bury anything in a steel shipping container you don't care about if you loose it. People have died in accidents with buried shipping containers, because they tend to be OK until they have a catastrophic failure- meaning you may not have time to get out.
There are a couple cheap but decent options.
1. Used single-wide mobile home. Replace the toilets with sawdust toilets, run the drains from the sink outside to a watsons wick. You can sometimes get OK older singlewides for a thousand dollars. For a grab-and-go solution, it's not a bad one.
2. For a lot more work, the $50 and up underground house books is worth it's weight in gold. I have a copy (plus the greenhouse book, plus the DVD workshop) and they are fantastic. It's how I am planning on building the shelter for my family at our BOL, but mine's gonna cost a bit more than $50- I'm going to hire some nice young men with heavy equiptment to do most the digging.
3. Earthbag housing- Owen Greir, I believe, is the go-to man there. More work, but more of it can be done even by very young children. Bonus points: if you are worried about WROL living, they're bullet proof and bullet resistant even to fairly large calibers.
4. Hexayurt- 8 pieces of plywood and you have something much nicer and roomier than a tent, to stay in while you get your main structure built up. Not bad.
After having spent a lot of time walking around them, playing with them, and looking at a wide variety of alternative building structures, I have to say that the Mike Ohler stuff is #1, follwed by the Earthbags/sandbags, and everything else comes after that (strawbale, cordwood, etc).
There are more options but you'll have to do a lot more research on them, and they're a lot of work- rammed earth, rammed tires, tire bales, and compressed earth blocks are all awesome. I'm seriously tempted by some of the CEB presses out there, and thin shell Catalan tile roofing is not only beautiful but strong enough to bury (almost as strong as steel reinforced concrete), but I'm going to have to teach myself from Spanish language videos on YouTube.
What will work best for you also depends greatly on what your local weather is like- what's your water table? How many days of winter heating will you need vs. summer cooling? Etc.