Canada when it comes to buying. CaVirtex is a very good choice. One thing to keep in mind over the years is that the price in Canada for BTC tends to be lower when compared to the large worldwide exchanges (Now Bitstamp) when one also factors in the CAD / USD rate. A possible explanation is Canada's cold winters making it more cost effective to mine BTC in Canada than in other parts of the world. This makes Canada a net exporter of BTC and tends to depress the price in Canada when compared to world markets.
The heat produced by a bitcoin miner is way more welcome when it is -35C outside than when it is 35C outside.
Amen to that if there is one thing we can be greatful for its the bloody cold winters here that make mining profitable
Liquid cooling I got your cooling right here
Go outside when it is -20 in November through January puts the Miner in a greenhouse/shed and wire an internet cable from the house and watch the miner run fine since it keeps at around room temperature lol.
(Maybe some humidifiers just in case though)
I think though that its fine apparently there is a picture of a rig on a roof covered in snow lol not sure where though.
https://bitcointalk.org/index.php?topic=35470.0If you want to go with the exchange rates there is always mintpal as well for arbitrage trading between different currency pairs.
Or two accounts one to buy bitcoin and one to sell those bitcoins at a profit.