Used does not matter, unless it is damaged, or some REALLY old model.
I got my Pieps on ebay for 75 bux 3 years ago, it was used for testing in Utah and sold by a patroller. Works perfectly in practice sessions and with a Pieps you can update the software at a local shop.
Ebay has used beacons because people buy AVY gear new all the time and never use it, realize they are in way over their heads and sell their whole kit.
Probe, used is fine.
Shovel is a shovel, new or used.
Avalung, buy new.