Painting canvas...

On Benito Juarez across from the the supermarket (or thereabouts) is an art supply store. Failing that, track down Grace Relf. She'll know.

Try Mayren Navarrete. She has an upstairs studio across from the parking area behind Scotia bank. She can make you a twice-primed canvas any size you like in about a day. Much higher quality and better price than a commercial canvas.