Sams recently started carrying Plano cases with wheels that are about the size of a footlocker. Price: $14.67 plus tax.
It fits suspiciously well into the trunk of my car, and fits all the crap I always have in there (trunk bag, blanket, toolbox, air compressor, socket set, crowbar). It is also not lost on me that an AR-length rifle would sit neatly inside.
They have two buckles on the front and one on each size. Everything is overbuilt and sturdy except the hinges. When the box is closed I’m pretty sure I could throw it down a flight of stairs full of rocks and it would survive. It has rollers on one side, but with no extending handle they aren’t practical to use unless the contents are heavy enough to merit crouching to pull the thing, or you are short enough that the side handle is at a natural position while walking.
And they have notches to stay lined up while stacked. I think I’m going to have to pick up half a dozen of these. They beat the ever-loving snot out of rubbermaids.