1970 or prior year Bonneville's are a "collectors" choice. 1971 to 1978 one might call "special Interest" bikes. The former in pristine condition ~$10,000 USD +/- The later can be found for ~$6,000 USD, but most of the bikes you come across are not pristine in spite of the price their current owners are asking for them.
FWIW they aren't all that unreliable for bikes of that vintage. You do need to keep on top of things. The application of newer adhesives; For example: RTV Sealants, Hylomar and Red Loctite have greatly improved the half life of these machines. My '71 shown below.
Last edited by Bluehighways; 08-31-2018 at 02:21 AM.