Re: New to the sport
I have a pair of '99 Yamaha GP760s and I think they're great for the first-time jet skier.
Plenty of power, seats two, comfortable, they handle well, have a few bells and whistles, but not too many, and you can find them for pretty cheap.
Yamahas have been known to last for basically ever, especially in saltwater. Maintenance is easy, and likewise, servicing them is also easy.
As with anything, though, the newer the better. Look for something with low engine hours, and make sure to check the engine compartment for signs of corrosion or exhaust leaks. While these are not inherently bad, they can be signs of future problems.
Also, after every ride, make sure to connect a hose to the valve, turn on the engine, then turn on the water, let the engine run at idle for about 3-5 minutes, disconnect the water, and then cycle the throttle for about 15-20 seconds to get all the water out of your cooling system.
Finally, after each ride, spray down the inside of your engine compartment with WD-40. It keeps everything in tip-top shape, prevents corrosion, and keeps it looking shiny (e.g. helps resale value!)
Have fun!