O I C now ... hmm. Both my sons built 'chuck boxes' for group camping using ideas from Scouting. Started with a $19.95 kitchen cabinet (no interior shelves) from HD/Lowes, then mounted hinges to the corners and added 2x2 legs, sanded smooth and finished.
If you make your own plywood box (it's good practice for tear construction) and buy hinges and framing materials you can probably duplicate the whole thing for $15 or less.
You want one sheet of plywood (we used quarter inch sanded one side), four pieces of 2x2 8' long, and 2 pieces of 1 x 3 8' long, two sturdy hinges, some sandpaper, some wood screws and your choice of finish.
I like making mitred corners on the framing; I use the 1x3 for 'face frames' and have found that I can handily operate a 'lift-lid' with finger grooves.