Roti Canai in Montreal?
The only place I've seen/had Malaysian-style roti canai in Montreal is at Restaurant Thai & Pho downtown. It's about $4-5 and includes a bowl of dipping sauce. They have plain/chicken/veggie variations of the sauce and some other options I'm probably forgetting.
Restaurant Thai & Pho
1801, rue Sainte-Catherine O
If you're looking for just the bread I haven't seen that anywhere but the first place I'd check would be Marché Hawaii in Ville St-Laurent.