Ha, thanks for the tip, Kelvin! I certainly don't know "all things" Legend but I've owned 8 of them and been an active member of the online enthusiast community for a decade and been to all 8 NALMs (Nat'l Acura Legend Meet).
A 1989 with 500 miles on it is a truly rare find. As with any 23 year old car that's sat most of its life, you already know it'll need some help to bring it up to any kind of solid mechanical condition. A friend who works for Honda told me once that the cars used for "training" end up getting crushed or disposed of because they're no longer saleable. Yours must not have been among those.
As for resale value, aside from a couple examples (a last-production-year, 1995 LS Coupe 6MT with ultra-low miles, for example) the Legend isn't really a collector car. Your post didn't specify whether the car's a coupe or sedan, stick or automatic, Base, L, or LS Trim. Those factors will all greatly weigh into the overall desirability of the vehicle. Pictures would be great.
Check out the
Acura Legend Forums, 1st Generation section for some great information. The
Wiki Page there will also help address some of the basic questions about the model and its history.
Good luck with the new acquisition and congratulations!