Sorry Jake I don't buy that.
I agree that quantity plays a big part, but not to the extent that we see with boats. The mark up on boat bits seems to be in the order of 500% to 1000% , hobie v generic, the mark up between a car OEM and generic is only about 50% to100% at best.
That said the casting is probably not a good example because of the up front tooling cost, (thats why you don't see big castings on cats anymore). But you can take almost any other component on a cat and see a similar mark up. Most catamran frames are made up of Aluminium extrusions which should cost $1-$2/kg to manufacture. When Hobie sell you a bare tiller tube they are putting almost no added value into that themselves but you are not getting it for $2/kg!
The previous posts are talking about the same (generic) product being sold at a higher price to a different sector of the market, there is no volume consideration in the equation.
All the best
Gareth