Every major Canadian bank lets account holders purchase foreign currency at any branch, the rate is worse than the interbank rates but not by much, maybe 1-1.5%. There are no additional fees beyond the exchange rate spread to do this. Common currencies like USD, GBP and EUR would probably be on hand and others would be ordered in. This service of course excludes countries that have severe currency controls like India, Argentina, China etc. but I've not had difficulty getting some fairly small time currencies like Philippine pesos.

It's the easiest way to do things if you need a small amount of currency to tide you over when you arrive, or a large amount that is too much to get from a local ATM.