So I currently have a set of 250mm (about 10 inches) carbon fiber rods for my rails, I need some longer ones. I think the next common size is 450mm (about 18 inches).
If you can't find em used, I'd check out IndiFocus. They have their indiRAILSpro with 18 inch carbon fibre rods for $149, and I bet if you call they'll sell you just the rails.
