Assuming that sewing machine portability is not important, you might want to look on craigslist for a made in US, Japan or Germany industrial, compound walking-foot -- has both drop-feed (bottom-feed) and needle-feed (top-feed) with an alternating presser-foot -- sewing machine. Very nice to have features are reverse (some early machines do not), a large bobbin and a servo motor. Unless you want to do sail work, zig-zag might not be too important. The following links might be helpful, and do click on "show more" on the video.
Walking foot sewing machine in action - YouTube
Sailrite is a good source for materials, notions and tools, and also for video tutorials. The Sailrite sewing machines are reported to be made in Taiwan or China and do not seem to have a good reputation with folks who sew canvas for a profession.
You didn't ask but I think that the following books are worth consideration, especially the Casey Book:
The Complete Canvasworker's Guide by Jim Grant
Canvaswork & Sail Repair by Don Casey
The Big Book of Boat Canvas by Karen S. Lipe
Just for clarification, I am a beginning sewer -- have completed about 10 projects -- with a Singer 111W155, with none of the nice to have features, that was acquired via craigslist for $325, the clutch motor being replaced with a $125 servo for speed control and safety.