Supercharged rides aren't for everybody. They are fast and they are a blast (I couldnt imagine going back to a non SC ride) but they have greater $ maintainence requirements that some dont care for. I'd be wary of an '04 unless it had solid maintainence documentation, unusually low hours, and satisfied a thourough visual inspection, complete with a 15 minute water trial. NO RIDE NO BUY. PERIOD. Now if it has flaws, and you know about them up front, as well as what costs would be involved to fix it up, thats another matter.
The supercharger clutch assembly from '04-'08 were suspect and notorious for failing. Ceramic washers were the culprit, and were known to fracture and break apart causing engine failure. They MUST be removed and replaced although Sea Doo denies fault. If I was considering purchasing this ride, the washers would certainly have to have been replaced (with supporting docs)
Lenghth of service and durablity comes down to the owner in most cases. Properly maintained and not abused rides can fetch hundreds of hours of use.
Winter is a buyers market. Read posts and threads pertaining to your situation... theres a TON of good info on this site provided by some very sharp people.
Good Luck to Ya