You should be able to find one in good condition w/no-more than a need for new tires or brake pads or a battery for $2.5K for an '89, in my opinion. The more-stock, the better, as far as I am concerned. That way you get to make it as you wish. Actually, you should be able to get something a lot newer for ~$3K. Does it appear to be well-cared-for, no oil/fuel/coolant leaks, starts right up, revs cleanly, no slop in the steering head (put it onto the centerstand, then use a friend on the passenger seat to swing the bike's center-of-balance onto the rear wheel, then grab the bottoms of the fork sliders and see if there is any 'wiggle' trying to move them forward & back. Or, jack up the front of the bike to do the same thing.
Second gear tends to go even if you don't drag race the bike, especially at about the mileage you have there. If you can run it to redline in 1st and hit 2nd, and get right back into the gas, and go full-throttle to 3rd w/o having it jump out of gear means it probably doesn't have the dreaded VMax 2nd gear issue.
An '89 which has the original fork oil probably needs fork seals because they are original and because the downtubes are chipped. That tears-up the seals, leaving the sliders dirty with puked-out oil. Are the sliders black w/oil? The rear shocks, well they probably 'don't.' Look at the fluid levels. Open the clutch & front & rear brake master cylinders and see what the fluid looks like. If the brake/clutch fluid is opaque, or nearly-so, a bad sign of little or no maintenance. Fixing a bunch of things like I have just described can easily go past the cost of the bike if you just told a dealership, 'fix these things.'
Now you might like in a part of the country where these bikes are not too-common, but I see much newer bikes here in south FL for not much more, and I bet they are in better shape than an '89 that has not been maintained. You can burn thru $1K pretty-quickly fixing things that are worn-out and need replacement before it's safe to use, especially at the speeds these are capable of.
Also there are the 'incidentals,' such as a new quality helmet, new boots, & new gloves, all of which will keep you as safe as can be while on a bike.
Remember 'cash is king,' especially in this economy, "asking $2.5K" means you should be able to get it for somewhat less, especially if any of the things we mentioned are there. Don't be afraid to walk-away, after leaving your phone #, you just may get a call-back when he doesn't turn-up any other 'cash-in-hand' buyers.