sail boxes; why so expensive?
 

You've probably seen these boxes, usually on a catamaran trailer. They're a
pretty simple fibreglass box, a foot high, maybe 2 feet wide and as long as
the boom on the boat. Why do they cost so much for what they are?

Is it worthwhile trying to build rather than buy, or is this one of those
things where you're just better off paying the money?

Thanks,
Shaun