This is going to sound a bit strange but try a wholesaler that sells materials to the 'Dried Flower arrangers'
We have a place nearby called 'Country Baskets' that sells amongst all things, different reeds, canes, peacock quills, etc.
Try them, they may deliver or put you in touch with somewhere more local:
Country Baskets Leeds
Ardsley Mills Bradford Rd
East Ardsley
Wakefield
WF3 2DW
(0113) 218 9090
Regards, Dave