As was mentioned earlier, price really drops when you take the casters away which I am assuming could be found at Harbor Freight for MUCH less. These ones are huge!
But they do support 450 lbs. and the price is right. I'm guessing the bolt pattern won't match though.
2x 8968K26 Galvanized Low-Carbon Steel 90 Degree Angle Perforated, 1-1/2" X 1-1/2" Legs, 5/64" Thk, 6'L $8.66 each $17.32
6x 4664T65 Steel Perforated Flat and Angle Framing Angle, Hot-Dipped Galvanized, 2-1/4" X 1-1/2", 6'L $11.64 each $69.84
16x 4664T22 Steel Perforated Flat and Angle Framing Galvanized Steel Corner Plate, 6" X 6" X 6" $2.25 each $36.00
2x 4664T61 Steel Perforated Flat and Angle Framing Hardware: Zinc-Plated Steel Bolts W/Nuts & Washers, packs of 50 $6.45 pack $12.90
Of course, this is not including S/H. How do you find out if there is a local warehouse (Will Call???)? No idea what a Will Call is.