Personally，I recommend a linen canvas, I've been using them for a couple of years and they work wonderfully with any paint thinner and aren't that heavy (depending on size) you can paint several layers on them and it won't rip easily or anything. Canvas is cheap. If you build the stretcher bars from scratch it's maybe a quarter of the cost of a stretched canvas. Maybes less. Linen is really pricey but if that doesn't bother you it is really nice to paint on. I stretch a lot of canvasses in the 5–6 foot range and a piece of canvas for that is maybe 10 bucks. Linen would be closer to 100 and that's assuming a bulk discount for buying 10 or more yards.
I used to stretch my own canvases but haven't been painting for a while anyway. I would like to resume painting soon. The last time I painted was in oils, in a life-model setting, using linen. The linen was really nice to paint on and I would use it again money allowing. If you're broke, sturdy cardboard is good to paint on and I have used it many times.
