How about archery supplies or kite supplies?

I usually make my fittings myself from dowell, nothing special.

The cost to tool up for carbon tube manufacture would be high, I doubt if the volume for pushrods would be worth the investment so my guess is tube comes from a more common source like those above.

You know the story, buy the common or garden variety item, [sm=idea.gif] paint it purple [sm=greedy.gif]& before you know it everyone's queing up to buy it at 20 times the price! - John.