At one point I decided to move over to bamboo or birch needles but don't really get on with them.
I have the following for sale (these are all unused or used only once - all in their original little plastic sleeves:
Prym bamboo circular needle size 6mm 80cm long £4.25 including postage
HiyaHiya Bamboo circular knitting needle size 7.5mm 100 cm long £3.25 inc postage
KnitPro Basix Birch circular knitting needle size 12.0mm 150 cm long £3.25 inc postage
KnitPro Basix Birch circular knitting needle size 10.0mm 100 cm long £3.25 inc postage