I checked with MA a few months ago on getting replacement AXS trim panels for my rack. I picked up a free AX-S and am using it freestanding. I took the rollers off and am going to put some casters on it. I plan to use the SnapAV hardware to finish it which of course does not match the brushed anodized finish. I asked if they sold them in the black powdercoat finish. Not only did they inform me that they did not, but also that they did not sell the trim panels separately, as you have found out.
How much do they want for the "kit"? Or what is the part# so I can look it up.
I am going to take the bottom and top panels I have and sand them and paint them and see how it turns out. There are several custom metal shops within a stone's throw of our office if I make a mess of it. :)
"When I eat, it is the food that is scared." - Ron Swanson