I came here to exchange some currency for international travel. The markup was about 1.3% (excluding their $3.50 flat fee), which is pretty good compared to other options (banks, airport, etc). Payment can be made in cash or debit. Service was very fast because there was no one else here and the person behind the counter was extremely fast at counting cash.
They have a policy where if your transaction is $1000 CAD or more, you can return the unused portion of foreign currency and convert it back into CAD at the same rate if you bring back the receipt. The exchange has to occur within 30 days of the original transaction and you can only return up to 50% of the currency that you purchased. There is no service fee on returns.