I guess if you have bad firewire that you are talking about the Aluminium DVI displays?
I'm afraid none of the internals are available as service parts from Apple. Not even to warranty centres.

Don't know what the US price would be, but I would guess it will cost over 50% the price of a new one to have yours fixed
without any labour. Though you'd only have to swap the foot over at a guess. Thats alot of cash for a firewire hub.