I've searched so many times, looking for the Lego canvas in a normal fabric form - no luck. I believe Lego has this stuff made special for them, or it's made in-house by themselves.
So yes, Lego ship sails is where you will find it.
Art canvas is NOT the same thing. I heard years ago, from an "inside source", that Lego has it special made just for them.
Is this stuff you guys are talking about the same stuff that is used to make the capes and such on the figures?
And if it's as simple as popping into the local art supply store to get sheets of it, that would be mighty fine...