So I ended up buying a 'cheap' mahogany ended 20b Lachenal. Not in pristine condition, but it has character. Seems mostly in tune, all buttons are working, and I have been able to learn a bit, but there seems to be a pretty serious leak in the bellows. I can feel air on my face if I hold it near enough. I don't have enough air to play for more than a couple of seconds in one direction.
I think I might send it off to someone for repairs (don't have the time to do the work myself).
And Alex, thanks for the offer, but I'm up in the North East.