I did end up going with Middle Atlantic. I purchased from showmecables.com instead, though:

Slim 5 Series Equipment Rack Enclosure - 20 In. Depth - 37 RU

SH Series Zero Space Rackshelves - 20 IN Deep

I bought two of these Zero Space shelves for the 20" depth rack, though I'll probably get two more. I'm going to be buying one more of these Middle Atlantic Slim 5 racks, except at the 26" depth, which I'll also get two of the Zero Space shelves for. I'll buy sliding shelves for the printer and scanner, and after that, I think my gear will be sufficiently served by these Raxxess rack trays.

I was impressed with my first order from Show Me Cables. Most of the order took one business day to arrive, and the one straggler package arrived the following day.