Quote from psytrade:
bank of montreal will charge you .5% fee on 50k for converting into a USD account. This may be higher for you, if you are not a client of their firm..
Quote from Pippi436:
Have a look at that:
http://fxglobaltransfer.oanda.com
Its Oanda's physical delivery service. You can exchange cash on low spreads (2 to 3 pips for usd/cad) for $25 flat fee. Get a quote from your bank and compare if its worth the hassle. Retail banks around here charge ridiculous fees and bid/ask spreads on the counter, so it may be well worth it.
P.S. if you choose a fx firm for the conversion, make sure they actually use the rates from their platform for physical exchange and not some retail bank benchmarks. Other than Oanda i only know IB that does that (for small amounts anyways).