Commercially primed canvas is ready to work with immediately. The surface is uniform and has less texture than hand-primed canvas. Order canvas unprimed if you prefer to work with more texture and natural imperfections.
Local art supplies stores carry various sizes of blank stretched canvas. The canvasses are commonly made with cotton or linen and are offered primed or unprimed. Some stores carry jute canvas and other exotic fabrics. Blank canvases can be purchased individually or in bulk.
Canvas boards are appropriate for oil, acrylics and mixed-media. Other terms used for canvas boards include: art boards, art panels or canvas panels. Hardboard is covered with canvas, then primed with gesso or a similar ground. The boards are sold in art supplies stores but the selection can be limited. Online stores are another good source for art panels. Blank canvas boards are sometimes confused with gesso boards. Gesso boards don't incorporate canvas into the structure. The primer is applied directly to board.
Canvas rolls are another option. Rolls can measure over 80 inches in length and come in smaller sizes as well. The local art supplies store is a good source for roll canvas and it can also be ordered online. It comes primed or unprimed. Cotton and linen are the most common roll canvas available.