I bought a pack of stamps at the post office, that way I don't have to go buy a single stamp everytime I mail something and can just put my envelope in any mailbox. I also use no tracking if the trade is <50$. The stamps I bought are also "permanent", meaning they don't have a $ value, stamps that have a $ value give you headaches when they raise the shipping cost by a few cents, then you are stuck with 1.10$ stamps when the cost is 1.13$ hehe.
For tracking within Canada you need to use a bubble mailer and cost depends on the province you are shipping to/from but it is between 10-13$, you'll get tracking and fast shipping. Avoid the prepaid Xpresspost cardboard envelopes for tracking, they're terrible to mail cards and sometimes they get all bent because they're so wide. I only used tracking once though, so I'm not an expert.
Shipped with regular stamps for 30+ trades, never lost anything.