Having bought a MY98 with 82,000 miles three years ago (the equivalent of what you're looking at doing now) i'd leave it. I had a bit of bad luck and the bottom end went on mine at 96,000. To be fair the replacement (lower mileage) engine probably helped sell the car when the time came but i was lucky to get what i did for it with 116,000 showing. The thing is, no matter how great the service history is absolutely every non-serviceable part on the car is 89,000 miles old - bushes, springs struts, drop links, gearbox the lot. Although it will feeel fine to drive it will be soggier than a 30,000 mile equivalent as i found out.
Unless it's dirt cheap i'd leave it. Bugeyes aren't rare and seem to be cheap enough due to the questionable styling. Hang on for something you don't need to question to see if you're making the right decision.