or can afford. Cotton duck or linen, or maybe one of the synthetic fabrics? Buy by the yard and do your own stretching, or ready to go? Canvas panels vary from a sturdy cardboard, plywood composite and others, your choice depends on the type of paint you plan to use, and your available funds.
Frames come ready made or sold by the individual fitted boards for DIY projects. It's not hard to do with a couple of common household tools.
Then there's the priming medium. Priming creates a protective barrier between the canvas and the paint to help your artwork look its best and last a lifetime. Typically you apply several coats of gesso or traditional hyde glue and oil priming white. You can also find recipes for mixing your own primer.
I'm an old school DIYer, so I do my own stretching using a mid priced cotton duck. I still use some canvas boards, practicing, testing a new paint or trying some different technique. I also use boards for little gifting pieces because it's easy for the recipient to pop them in a frame.