Hi all,
Yamaha still makes the Superjet and they are saying that it is for closed course use only:
http://www.yamahawaverunners.com/superjet
Kawasaki no longer makes stand ups. They stopped making the 750SX-R in 2011:
http://www.motorcycle-usa.com/805/10...irst-Ride.aspx
This was Kawasaki's last attempt at popularizing stand ups and it has a more forgiving hull design. It does require premix which is a bit of a pain.
For someone learning to ride, a good option is the Kawasaki 650SX. They made these from 1986 to 1993 and you can still find them around. It has enough power to be a decent ride and it was designed for the recreational rider. Craig's List tends to be a good source (example):
http://boston.craigslist.org/sob/mcy/4557740828.html
I would strongly recommend opting for one that was not used in salt water and carefully check condition. The 650SX did not come with a handle pole spring, so if you go that route, I would strongly suggest installing one to minimize arm fatigue.
Good luck.
Jetskier