The NAPA cart is made by Homak, Homak and Waterloo make the majority of the bolt together carts for many of the other tool companies. The Cornwell carts are pretty nice,having the extra drawers and NAPA was selling an identical Homak cart last month for $399 which was a steal compared to Cornwell's price.
Of note the Waterloo cart is made in China, so the Craftsman is too. The Waterloo has a higher weight capacity versus the HF and the Homak units, but the only difference I could find is that Waterloo has two folded steel runners that goes in between the casters and the bottom pan, there by stiffening the bottom end of the cart. So if you guys add some steel across the top of the casters that tie them together and better supports the unit, you'll be increasing it's weight capacity. All three carts, HF, Homak and Waterloo were within a few thousandth's in thickness so I believe they are even the same gauge of steel.
TheGrooveking