Am assuming
@Aaron Harmon is a rebreather novice. Would strongly advise against a second hand older rebreather unless you’ve got an "expert" with you and there’s a guarantee with the unit.
A close diving friend bought an Inspiration Vision which has cost him a small fortune to fix up: lungs fell to pieces, $1300 for a head service (electronics replaced), endless hose issues, cells, cylinder testing and cleaning, and a replacement case. He admits that it would have been better to have bought new…. It was out of the water for months.
It’s one thing if it’s your second or subsequent rebreather where you roughly know what you’re looking for.
On the other hand I bought a second hand Revo that was like new with only 5 dives registered and struck lucky. Had to replace both HP hoses and some cells, but saved a load of money over a new one.
Obligatory car analogy: mine was a low mileage 1 year old Volvo, his was 10 year old Ford with 150k on the clock. Could you tell the difference?