I've been scrubbing the web for glass tube that is 6" dia. The cheapest was about $65 per foot if memory serves. Come to think of it, that was hard to find and the only 6" dia. anywhere.

Does anyone know of any good glass cylinder sources?

I know some people use Pyrex baking tubes. There area a bunch on Ebay, but I think they are only about 3" diameter.

Where do these guys buy the glass when they make the professional cool tubes? The average joe should be able to buy there too. The trick is finding the place. I've searched in the real world as well as the web.