Found a company called Carbonology who make proper carbon fibre parts to order... they have a spares/offcuts bin which has some very useful tubing suitable for tail booms 
Have a look :
http://www.carbonology.com/shop.asp?...93&sec_id=2116
Daniel.

Have a look :
http://www.carbonology.com/shop.asp?...93&sec_id=2116
Daniel.