Price is way too high imo, especially for USED rigs with such specs, a newer rig can be built from scratch with warranty on the parts...unless if you're willing to back it with like 3+ months warranty on parts etc...if you're serious about selling those systems on here, that price might have to be dropped considerably.
Not meaning to bring down your sale, I'm just being honest about it, and most other individuals on here would share similar sentiments, even if they don't say so aloud.