Here's a source for metric carbon fiber rods (this page is for solid rods, not tubes). The sound difference is remarkable, even on my inexpensive bass.
Following luthier Michael Hartery's suggestion, I got one of these and stuck one of Bob Golihur's endpin balls on it. Cut the rod in half and now I have a backup:
http://www.cstsales.com/metric_carbon_rods.html
Certainly not nearly as elegant as the wood turning, but it weighs very little, sounds good, and is inexpensive. Just another (low-budget) thought...
