This one sold for $475 but was a very rare and sought after Carotene Orange color. The original Power has never gotten a lot of love from collectors and so the prices have never gotten that high. That's why you see them parted out so often. People pick them up for under $400 and try to turn a profit.
Now complete dead mint, maybe you could get $500 if you found the right buyer. More if you magically had beehive knobs on it, but those didn't really show up until 1988.
Probably about the same as what I posted above. If you have that metal beehive knob like in that picture, that can fetch some extra bucks. But I wanted to point out that what you have is an '88, not an '87.