Best thing to do is put it on craigslist or on ebay. A dunstall will usually get fair money. If it is in good shape, possibly 4000. The rectifier is a myth. Mine is 31 years old and works just fine. If the wiring done poorly or the replacement unit is poor, then of course it can die and that usually how they die. The factory unit though is pretty reliable.
The ride IS the adventure. The destination is just to get gas!