http://www.softdirect.nl
Dutch supplier selling a variety of plotting knives for the Roland vinyl cutters.
They have their own brand of knives which are softer hence cheaper, but they also sell the original Roland knives by piece (many suppliers sell them in packages of 5).
Attached pdf describes (in Dutch) the Roland blades for CAMM-1.
http://www.techsoftuk.co.uk/
The Educational CAD/CAM Specialists
Supplier of various materials for cutting, milling/routing, laser cutting, 3D printing, engraving etc..
Also supplier of cutronic foil, a copper foil with adhesive backing to cut circuit boards using the Roland CAMM-1.