1st of all, it is very hard to give a price without at least a few decent photos.
2nd, if you really want to get top dollar, market the bike north of the 49th parallel. You are close enough to the border that lots of people from Canada are willing to come across and arrange the importation themselves. I have done it quite a few times.
that all being said, here in BC, a good condition and ridable R65 should sell for between $2-3000 Cdn. And there is a large BMW Airhead following up here.