That noted, take a look at the below video to see why shipping containers really won't become the housing type of the future. While the below is smarter than most tiny homes, not having a dedicated set of wheels below it, the builder ends up using some fairly specialized cutting tools to add doors and windows, and then ends up framing it in with standard 2x4 framing, reducing the home in size by about a foot in length and width.
In other words, what he got for that $2k-6k was essentially siding, shingles, and...a likely horrendous water vapor issue. Keep in mind that the outside of a shipping container keeps water out and in for a ~30 day transit by sea. However, siding and Tyvek on a standard home are designed to let water vapor out to prevent mold in the walls.
To fix that, you've got to add another $1000 or so to upgrade standard fiberglass batting to closed cell foam. In other words, the ~ $1000 he would have spent on shingles and siding is now replaced by $3000-$7000 for the container and specialized insulation.
Worse yet, to get ~ 230 square feet of home, he's got an extra 30% of wall area (heat loss), a flat roof (water leakage again), and a choice of either a very low ceiling or low insulation in the attic--where it matters most. There are great ways to make a compact home, but this isn't one of them.