Check out this DIY Wooden Squat Rack construction.
Looks pretty sturdy.
Material:
- 3 6×6, used for the base and stands
- pieces of 10 gauge steel (0.1406″ or 3.57mm)
- 24 2×4
- 5 lbs box of 3.5″ screws
- 2 bottles of wood glue
Cost: around $160
Also check out this Wooden DIY Power Rack.