That's a hard call............
OK....
The 2003: There was a small change in the hull, and it is supposed to ride nicer, and come up on plane faster. With that said... I've been in a few Islandia's, and when they are running right, I really couldn't tell a difference. (so take that with a grain of salt)
The low time isn't a factor when you are talking +10 years. A poorly winterized boat (assuming NJ) could leave you with a drive that is messed up, from ice forming. Also, assuming NJ... if it's seen salt time... then corrosion is a factor. One thing to keep in mind is that water is in the exhaust, and that will vaporize and condense in the engine. That's why you "Fog" the engine when it's going to sit. Since it (supposedly) very low hours... that could be bad, since it wasn't run enough to keep the internals clean of rust. (and covered in oil)
Also... in 2001-1/2, Mercury changed the engines some. That change showed up (generally) in 2003 for seadoo. I value the 2002 engines higher. There was updates to the entire fuel system, and charging system... and the oil injection became bullet proof !! (assuming it's maintained) Also, it could have a bigger engine. The 250hp was in some of the 2003 boats.
SO... I would have the owner send you a picture of the engine.
$10k is a good price, assuming the home grown upostery isn't totally half-assed. BUT... if you are good with your hands... that can be fixed for a few hundred $$$.
Finally... there is an hour meter on the Merc's. It's just built into the computer. So, you will need to take it to a Mercury dealer (not a seadoo dealer) to read it out. (or find someone with a Rinda, or Quicksilver DDT system)
On the 2001:
I would only move to that boat if the owner said the engine has already been replaced. If it hasn't... it's going to need it soon. (well, so will the 2003, but it's a better platform to start with, assuming it has the newer style engine)