Amy, this is a great question since you are going to Montreal for surgery. Now, assuming you are not from Canada, you should watch the exchange rate and try to buy Canadian dollars when your country's currency is stronger. The nice thing about Montreal, as the others have mentioned, is they don't require all the money right away. So, if the exchange rate is doing really badly, and there is speculation your currency may become stronger in the future, you might want to hold off on making a full payment until the time you think it will be at the most advantageous. On the flipside, if you wait, you also might end up paying more if your currency becomes weaker.
For example, here are some sample exchange rates for USD/CAD and what it would cost you for $18,000 CAD:
$18,000 / 0.95 = $18,947
$18,000 / 1.00 = $18,000
$18,000 / 1.03 = $17,476 (today's closing rate)$18,000 / 1.10 = $16,346
$18,000 / 1.25 = $14,440
You get the idea, the higher the USD/CAD exchange rate, the less money it will cost you. Of course, people have full-time jobs speculating currency, and no one really knows where the rate is heading at any given time.
http://finance.yahoo.com/q?s=USDCAD=X Please note, the bank that does the exchange will typically have a lower exchange rate than the one quoted on the yahoo website.
If you are from Canada, disregard what I said because you are paying with Canadian dollars anyways so it's 1-1. If you are from another country besides the US, use the exchange rate for your country.
To answer your question: no, I didn't pay the entire amount up front. I saved a few hundred dollars by doing so, but also had I made the exchange a few months earlier, I would have saved over $1,000. The dollar was very volatile at the time.
(Disclaimer: this is solely my view and opinion and not intended as financial advice, please consult a financial advisor before making any financial decisions.)