I had a carbon tube made up for my GSO 10" f4. Landed in Dunedin NZ for under 1K NZ last week. That's including GST(15%) and freight from Germany.
http://www.teleskop-express.de/shop/...elescopes.html
I had holes drilled for my Moonlite focuser and the focus position moved up the tube a bit so I didnt require an extension tube.
Dave