15 to 17K depending on how well it runs and what service records the owner has. Proper maintenance on these is what prevents them from blowing motors at 60k miles like you hear so much. Also is it stock? 84,000 miles is a lot of miles for even a lightly modded FD, they only seem to be completely reliable in stock trim, it's when people start changing things, overheating causes increased wear and then -BLAM- that's where the bad rep for rotaries comes from.

EDIT: I missed the unmolested part, yeah a good 17 or maybe even 17.5k with service records, hovering around 16.5k without them.