Plastic tubing rules and so does Graeme (picturetrader). He's an outstanding seller and uniquely efficient shipper.
Like Schan, I also frequently use plastic tubing (called PVC in U.S.). If you know where to find thin-walled plastic tubing it's actually easier and less expensive, in my experience, than buying traditional cardboard tubes in bulk. The trick is using thin-walled plastic tubing not thick walled. Thick-walled tubing is heavier, costlier and overkill.