Get 4drawers from office desk
2-1/2"x2-1/2"x1/8" angle welded perimeter frame to sit them in
4 locking casters
3/4" ply wood on top
Cost me about $140 in total
$200 Canadian solution
I bought 4 office desk drawer sets - you know - roller bearings lockable..etc.
Welded a 60mm x 60mm angle frame with 4 2-way lockable casters. Plywood deck, UHMW screwed on top.
A power bar in the side and a 1/2" hole for a desk light.
Not nearly as nice but it took 2...