Plan on having to replace the fuel pump (if it's never been done). The pump itself costs over $600.
The motor is great on gas and performs nicely when it runs. Unfortunately, it can be very finicky and difficult to diagnose/fix for the home mechanic due to the complicated high pressure fuel injection system and electronics.
A rebuild also isn't very easy for a reason I forgot - something to do with high temperatures and high compression. Seems you can't just bore up in size and expect to be fine.
I'd say if it runs good, has good maintenance records, and will not be used a lot - go for it.
For more advice, you should probably try
www.pwctoday.com or
www.greenhulk.net.
Maybe board member WFO Speedracer has some more advice, he knows his Seadoos.
PS: I fix skis on the side and I will not work on DI's. I don't have the tools for it.