If your Havasu
is something like this one (shape, not condition) it may also be called an Astro....
My Havasu project
I wouldn't get too excited about the "Rare" factor.
I just bought a similar Hunter Compact-II, in-process restoration project, for $1600 and thought that was a good price. Again, it's all about condition, condition and condition. List it here and on Craig's list for starters. I would include the words "Like a Hunter Compact" in your ad, lookers use those as search terms.
If you are real brave, you can try eBay.