Here is an Ebay auction for a very unusual used FoMoCo Hipo distributor by Ebay member "monkeybus72" with a Buy-It-Now of $1,200.00:
Rare Complete original Mercury Comet Cyclone 289 HiPo FoMoCo housing dual point distributor used condition #C5GA-12127-A
FoMoCo housing part number C5GA-12127-A. Date code 4JD Original used condition.289 FoMoCo HiPo Duel Point Distributor C5GA-12127-A Mercury Comet Cyclone | eBay
-Fred-
Interestingly, as rare as a 65 Comet is with a Hipo 289, this distributor is the one for the optional transistor ignition which is even more rare. This distributor began life as a single point version rather than dual points. Mercury used the standard single point set rather than the lightweight point set used in the 427 transistorized ignition for some unknown reason. Ford specified the tan high performance distributor cap for this distributor.
-Fred-