Your Sea Doos have the 718cc motors(85 hp stock) in them. Very reliable when maintained correctly, are fun to ride, and are stable when riding and reboarding. These skis are based off the Sea Doo GSX platform, which boast the 787/800cc engines and RAVE valves for higher power output with 110hp(stock).
You could easily remove the spark plugs and see if the motors turn by hand. This would be a good selling point because the motors would not be locked up and freely turn. Worth more money this way. Updated registration also is a good selling point.
Keys that are programmed to the MPEM are also a great selling point. No need for the buyer to spend extra money at a dealership to have the key(s) programmed.
Lots to be said here from a maintenance point of view. But these basics mentioned would help get a sale going at $1,500 each.