Motocompos are baseline $3-4k at this point. Whether you're importing from EU or Japan.
The only reason mint examples are so plentiful, is a) because Japanese culture highly values maintenance, and b) they're small enough where people could store them in basements/crawl spaces out of the weather.
I have worked on and ridden a Motocompo and they really are VERY cool. Engineering and aesthetic blended better than almost any other moped. That said, I will never own one, hence why I have an Italjet Pack2, all the mini fold-up moped, none of the collector value.