https://wccftech.com/apple-is-now-selling-mac-pro-wheels-kit-and-feet-kit-for-699-and-299/

If you bought a Mac Pro with feet, you now have the option available to order a set of wheels for your machine. That's right, Apple is now selling the wheels and feet separately for the 2019 Mac Pro via individual kits. However, individual kits are pretty expensive as well much like the Mac Pro itself. If you're looking to get them for your machine, you will have to shed a couple of hundred dollars for each. Scroll down for more details on the pricing.

If you have the Mac Pro with feet and want to give your machine some mobility so you can easily move it around, the Mac Pro Wheels Kit is available at $699. It will get you four stainless steel wheels that you can install. Take note that if you're buying the wheels as a package with the Mac Pro itself, they will cost you around $400. What this means is that you're paying $200 extra when you buy the wheels independently.