canvas

Hi everyone,
First time user, and have a lot to learn about using the site, we have been building our own camper trailer now for a couple of years, photos will follow eventually. We have had $6000 - $11000 for canvas work, which is way out of our budget and seems absurd.
We have decided to do the canvas work ourselves, and as we have built everything ourselves, surely the canvas work cannot be that difficult. Considering making a sample from some cheap material and using for the pattern for the canvas.
The question is, we are looking for advice on the best canvas to use, what weight for roof and walls and where to purchase at a reasonable price.
Have heard about ripstock, and waxconvertors and the more I hear the more I am confused and undecided. If anybody has some firsthand information we would welcome the chance to chat. We are in Hastings on the Mornington-Peninsula.
Regards
Bill