ahhh waverunners so much fun.. i have two of my own, good times. i have two yamaha's and they might be a little different than what your looking at. so you wanna know what to look for? well check the hours meeter on it. that way you can tell how much it was used, if it has one. but i'm guessing it will since its a 97, you might need to turn it on to get the display to show up. and i would also check the prop, they started to come with stainless steal ones not sure when they started, but its good to know. you might have to take some of the parts off to look at it, and while your looking at it see if its in good condition. no big gashes and stuff. and check the hull for holes or cracks. there really isnt much to them but if you do get it, i would give it a good tune up, plugs, fuel filters, check the wiring, fuses.
as for insurance i dont have to insure mine but i'm in NY, it could be different where you are, and i also have to have a boaters licence to drive one. try calling your local coast guard office they'll give you the low down. as for price you said 97, 4 cylinder so i'm guess its a 1200 or something, a 3seater. i looked at the blue book value it was around 3000 grand, but they listed two models. if that helps. also someone dropped out of the jetski market i wanna say it was kawasaki, but not sure, mabey someone else might know that one. just an extra tid bit.
one more thing see if they'll let you try and start it before you buy. but dont run it too long only like 30 seconds or so.
hope that helps good luck!!!! <img src="/forums/images/graemlins/cheers.gif" alt="" />