A posting on the Origami Boats mailing list pointed me toward Deep Blue Yacht Supply, Inc. I have no involvement with them, but they seem to carry a wide range of boat parts and gear, leaning more toward mechanical systems than the generic "boat stuff" you tend to see. Propellers, gear pullers, shaft seals, exhaust fittings and the like.
Might be worth a look if you are needing parts for your refit/build.
Deep Blue Yacht Supply is committed to providing all of our customers with the highest quality yacht supplies at the lowest price in the industry. So take a look around, as our prices on propellers, cutlass bearings, zinc anodes, and all other boating essentials will not be beaten.