If they are clean... the price is right.
As far as buying a used ski... it's hard to say, but just use your head, and don't be in a rush to buy. Look the ski over... it should be clean, inside and out. (this shows neglect) They should be compleat... including the owners manual. It's not a big deal if they don't come with the skis... but it's a refection on the person selling.
Low hours doesn't mean a thing with watercraft. Most people buy them, and then let them sit after the "Newness' wears off. (in some ways that's worse than high hours)
The seller shoudl be able to tell you exactly what oil he has been using. SeaDoo's only like API-TC oil. If he holds up a jug of TC-w3 boat oil... DO NOT BUY THEM.
Look inside for any signs of hull repaire. I personally won't buy a patched ski. Touch up paint (or gel coat) is fine, but no patched fiberglass.
When you get there, the engines should be cold, and then they should start relatively easy. If they have been sitting... it could take a few seconds of cranking to start. BUT... if the engines are warm... the seller could be trying to hide something by making sure they will start.
If that all looks good, take them fora test ride. They should start, idle, and accelerate as soon as you pop the throttle open.
Finally... you probably won't get a dealer to look at them for you right now. This is the beginning of the PWC season, and I'm sure they are EXTRA busy with fixing stuff that won't start. Not to mention, most SeaDoo dealers sell motorcycles... and that season just started too.
Good luck :cheers: