If you can find a local printer, see if it works out cheaper buying your own canvas. There's a wide range of quality available, from places like The Works up to proper artists sites like Ken Bromley or the SAA.
Honestly don't know how much difference it will make too your finished product, or indeed how bothered you are about that. I paint watercolours, and the quality of paper there is everything. But for acrylic/oil painters they can get away with primed canvasses especially when they're painting thick.
If the printer's adding quite a bit of markup on the price of his canvas, it might be worth looking at.