Are you after foam sandwich or timber?
Keeping in mind I haven't actually asked him about this, but, Matt Kelly at Victorian Sailing Supplies in Seaford, has a Mossie that he built (timber) and would probably sell it if poked with a stick, hes into Fireballs now.
You would have to talk to him about whats required to get it going, but it has hardly been used, is light and has been undercover (shedded) all its life.
Theres no harm in asking.
Regards