It might be helpful to check out Catrikes forum for sale section. I located our Roads that way, and both were local.
In relation to purchasing new or used...so far as I am aware there is not a retailer or specific shop doing work for or selling Catrike around Atlanta any longer. I haven't checked in a while but the Silver Comet Depot WAS a service location and retailer. I didn't find out till after we purchased. The reason I found them was that one of the trikes was an early version and I had LOADS of issue out of the steering due to it missing a bushing that was in the later revisions.
I liked both of our bikes and outfitted them exactly the same sans the longer boom I needed for mine. I put SRAM IGH on both and made them able to ride on anything. The only aspect I turned out not liking overall was the 20" back tire in relation to getting stuck in grass and things as well as the lack of bigger gear due to it. Overall with the frequency we were riding we found them to need fairly frequent service particularly in relation to brakes and chain (there is a lot of chain), the seats, and the idler. Of note, the front derailleur they were using at the time I recall as a Microshift and it was pure ****.
I know it sounds negative, but it's not. We rode them a lot and they were super duper fun.
If I had it to do again and actually thought we would ride them I would go for a model with the shock on the rear wheel before any other consideration, up front.