fbrieden,

Not duffle type but, Lowes and Home Depot both have gear bags. Synthetics I believe.

Carhartt makes a few sizes that seem to be popular with the iron workers. Not sure if they are canvas either.

What was I thinking?

Try Klein ... The guys that make the nose bags and pouches ...

http://www.kleintools.com/

Cheers,
jb

Edit - Senior moment ...

Check The North Face,

http://www.rei.com/product/804288/the-north-face-base-camp-duffel-x-large

It's a base camp duffle, waterproof, heavy duty zippers, the whole nine yards. I plan on getting one of these for my harness and climbing gear. The link I posted is for their extra large duffle. I've seen it at the REI store here near me and that thing is huge! Thought about a couple of these to use as luggage instead of my Samsonite while playing road whore. You can wear it as a backpack as well so it frees up your other hands. It's a bit pricey but the reviews on it are excellent from what I have read.

Shawn