I don't know if this solves your cost issue, but you might be better off with a linear
autopilot drive, intended to be used below decks, which has an internal
clutch. I can't imagine using a true tiller pilot, which has to be lifted on and off the
rudder tie-rod or some other steering component, every time it's needed. Plus, the below decks drives are much more robust than above decks models.
And, and this is a big and, the world is full of sailing stories that are due to too-small autopilots letting the crew down because they were undersized, or poorly
water resistant. There's always a temptation to use a
cockpit mounted pilot to go across oceans, and I believe it's far smarter to use them in protected waters, and under
power. If you're sailing across oceans, use a below decks drive, either linear-hydraulic or recirculating ball drive, and it will serve you well.
Chuck Hawley