Buying canvas and getting what you pay for go hand in hand. But there are some reasons to consider going with better quality canvas. If not you can always spend a little extra and prepare them. But it comes down to two question for most people. How much does it cost and what quality do I get to expect? The answer is that it’s up to you. The difference is generally in the weight of the canvas and the quality of the stretchers and the gesso or other primer. Really cheap canvas from China will start around 4 or 5 oz canvas versus the more professional canvas up to around 12 or 14 oz. They may good for practicing but there should be a line when it comes to using them for more commercial in nature you might want to give your work more longevity with better canvas. What does that all mean? The main difference will be in the tightness of the weave (basically down to thread count). Cheaper/lighter canvas will tend to have more pin holes, and is much easier to distort. Heavier canvas is also better if you’re going to be un-mounting and re-stretching the painting, because it will hold up better to the changes in tension. You are selling yourself as a brand and it’s up to you to decide what you feel is professional enough. Your name is going to be associated with the paintings and you have to choose whether or not you want to promote certain materials. I personally, try to use the best quality of paint and support I can because I like those materials and it’s the type of art I myself do invest in from others. Stretcher bars take a lot of abuse, especially from commercially stretched canvas. They’re there to keep the painting from twisting. Studios tend to warp the most, especially at larger size. Galleries still can warp but tend to do so less often because there’s more wood which makes them stronger. There are a number of companies make 2X2 stretcher bars that are really sturdy and my favorite. The quality of the gesso can also be important. That cheap canvas probably has one or two coats of gesso, lots of pin holes (which is a big no-no for oil based paints), sometimes will flake, crumble, or crack right off the canvas. Usually, high quality canvas has a higher quality of gesso. The grounds will be more absorbent (as more chalk and pigment is added to the polymer), is much more flexible (this could potentially be bad for oils), and usually there are more layers put on. Can you find other items to paint on? Probably. Polyester is actually making a stance as a high quality, highly archival support. Most things (humidity, solvents, etc) don’t ruin it. Oils and acrylics can actually be used on it unprimed, but I usually suggest some ‘gesso’ for tooth. What about wooden supports? Or paper? There’s a lot out there that can be painting on. If you are painting with acrylic, watercolors, tempera, gouache, or encaustics you can get away without gessoing the board. Problems can arise if you don’t, like off gasing causing discoloration of the paint film or a weird chemical reaction to the wood if it has been treated or weird absorbency issues. The best practice in my opinion is to size the wood and then gesso with a few layers. It’s also recommended to paint an x on the backside of your board to help from warping from the paint film tension on the front. A lot of people will paint on mdf or hdf board. Depending on where you live you can get a full size sheet cut down at the hardware store into whatever sizes you want. Warping happens a lot depending on the thickness of the board. And you also run into the problem of needing frames. I’ve also found that these, and plywood and chipboard, tend to off gas a lot; I’m pretty sure it’s due to the adhesive used to compress them. They also tend to be very absorbent and will suck up your paint quickly. You can get or make cradled board. It is essentially a small piece of wood with stretchers and crossbars behind it. The bars in behind take the stress and help prevent warping. These are usually made from birch or pine where I’m from. I don’t know where you can find stretcher bars online, I don’t paint on canvas often anymore. Just do some research and you’ll be able to find something. You can always use 1×2 and nail them together and soften one edge to make your own. They don’t have to be mitered at the edges, just stagger your long and short edges. I’d only recommend this if you have a lot of fabric laying around, as it can be just as if not more expensive.Golden’s Just Paint newsletter has a really good article on stretching canvas.