There's not much at all separating that Diamondback from a Walmart bike. The components look similar. The frame isn't especially good. REI will likely have more competent people assembling the bike, and their customer service is good. Otherwise, I'd pass.

A 10 year old Trek with rusty cables and fossilized brake pads, on the other hand, will generally have a good frame and might have decent components. Cables and brake pads are cheap and need to be replaced regularly anyway. I got an '89 Specialize Rockhopper on CL for $120 that was in mint condition. I replaced the tires (only because they were knobby), installed a rack and it was ready to go.

CL takes patience and a good eye, but it's the only place you'll find what you're looking for (assuming you're looking for a good bike for under $200).