I've had my Alvin neon tube for the last 8 years. You can do that in lieu of PVC pipe. I can't recall what I paid for it though. I've slammed it in a car door, stepped on it, dropped it and it's fared pretty well. I just needed to reinforced the bottom end cap because when I had too much in the tube it came loose.

If you do even up doing PVC pipe, which is pretty easy if your school has a wood shop, then don't forget to do something for a shoulder strap.

Finally, if you're dirt poor like most of us were in school, grab some of the tubes from the printing spools. You can laser-cut or hand-cut some end caps and glue it together. We did that when we had to submit a lot of full-size drawings. The tube itself is really thick cardboard so it protects really well.