Don, I have found that for a non judged boat, I can go to local heavy equipment and semi truck service centers (Mack, Kenworth, FreightLiner, Cat, etc.) and they have the bulk inner and outer cable stock on hand. Older trucks - still in service had mechanical tach's and occasionally need a new cable.
At our Kenworth dealer, they will cut what length you need, crimp the proper ends on - hand you a ticket to pay the cashier and send you on your way.
I've done this 6 times now.
~~~ Paul ~~~