I recently purchased a Cambro400 since we do a lot of entertaining, and after looking at this site, I knew I needed a new toy.
They offered a cart for the carrier -- $158.00. Now I'm not cheap, but I thought I could build one out of the scraps I had down in the shed. All that I had to do was buy four lockable casters from Amazon, with free shipping, for $42 and a weight load >500 lbs. I made the darned thing, put a light stain on it, and sealed it with two coats of marine sealer, to keep the rain off. Here is the cart, still drying from the last coat of sealer.
And here is the Cambro with a couple of 4" pans, resting in the new dolly. Heck, a little of my time and I save more than a hundred bucks, plus have the satisfaction of doing something besides sitting on my backside.
It's not a fine piece of furniture, but it gets the job done.