I’ve recently been travelling on the eastern side of Canada, namely Ontario and Quebec.
Along my travels I’ve chatted to other travellers, which confirms I found the cheapest deals to travel to/from and around Canada at the time (last month – May 2011).
When time isn’t of the essence, it’s a good idea to sign up for promotions as you can get cheap fares through Megabus. I got a CAD $10 fare from Toronto – Montreal, normally about $26+. Usually newer buses and decent wi-fi when it works (off/on)
To get from Montreal – Quebec City, go with Orleans Express. You can buy tickets on the fly (no fare difference) – departures every hour.
If you want to fly in Canada, WestJet seem to consistently have the best deals – however sometimes Air Canada might have a promotion to rival the prices. Be aware that fare prices do not include taxes etc, so they look cheap but roll over the price to get the total price.
To/from New York – Megabus or greyhound have competitive fares across the border.
To/from mid-west USA I have found Delta to consistently have fares around USD$200 one way to/from Canada (obviously depends on where you’re flying to/from).
From/to London, UK Air Transat have budget one way fares. It’s Canadian Affair/Thomas Cook if you fly from London (online booking available). Flying to London if you’re not a Canadian or US resident you have to call up their reservations team to book. Their online system is restricted to Americans and Canadians. Fares are about CAD $3-400 one way, can get cheaper and can be more expensive.
Travel safe and cheaply!