Sobey's carries a Canadian made line of Latin American style cheeses that are branded "La Vaquita". I'm not sure if they specifically have a Queso Blanco. We've bought other varieties when we've done tacos at home.
It's very easy to make your own. Gallon of milk and some lime or lemon juice or vinegar will net you about a pound of the stuff.
Slowly heat the milk to just under boiling (185F or so), take it off the heat, add about a half cup of the sour juice (half that if you're using vinegar), salt it, drain it through a cheese cloth, then tie the cloth up and hang it a few hours (I just hang it from a wooden spoon spanning a large pot, but you could use a faucet).
Replace the cow's milk with goat's milk and shazam, chèvre.
Hungry Pete
At LaFontaine and Richelieu in Vanier.
They have a good supply of productos latinos.