Forgive me for asking but have you used the system itself? Indeed, you do have quite a few different playing modes whether it's for solo/PB or competitive play.
Cannonfodder does bring up a very fair point about ricochets that come back to you. I used AttackSense at Socom Tactical's range a couple of years ago and the range is much too short, not just because it's too easy to hit the targets, my friend and I were pelted by a hail of ricochets - genuinely every other 4 or 5 shots came back to us directly or indirectly sometimes. Bespoke Airsoft's range is longer but there were still plenty of shots coming back to us from its AttackSense setup. Even Blackstone CQB had a few coming back toward me and its farthest back target is about 20 metres so twice that at Bespoke Airsoft's range or thereabouts.
I don't think the deals to be had are what you're looking for to be honest. As Enid_Puceflange alluded to, finding them used is going to be rare as they're relatively new and not a high-volume product where you'd find much of a used market. The only discounts I would expect to find are through volume purchases as a business.
