They are a division of the Pacific-Northwest-local dealer chain "The Mac Store" (formerly known as simply "The Computer Store".)
I have traded in four or fives Macs to them over the years, and bought two. (Specifically to/form PowerMax, not counting their main new-only chain.)
Always good experiences with the company. One of the Macs I bought was a refurbished PowerBook G4, and the optical drive failed after six hours, but I had no problem getting them to replace it on-site, rather than sending it in for repair, even though by the time I got back, I was out of the 15-day return period. (I bought it quite literally as I was driving out of town for a two-week camping trip. The kid made it through two DVD movies in the back seat before the optical drive died.)