Hi there, I live in Calgary too!
There are a couple of ways to find craft sales here -
1. Check the board at http://www.calgaryarea.com/community/eventspsa/craftsales/craftsales.htm
- many places advertise there.
2. Get out the map or phone book and call up community centers (I start around June)
3. I also call from these two lists of previous sales. If a community has had a sale before, chances it will be annual. Note that these two links are outdated - http://www.calgarysun.com/cgi-bin/publish.cgi?p=160633&x=articles&s=lifestylehttp://www.canada.com/calgaryherald/news/swerve/story.html?id=c39bc8b2-8fa9-4eed-8e66-023906af729f
4. Make friends with other crafters :-)
I am actually compiling a list of the sales to make into a brochure for vendors to hand out. You can check it out at http://www.purple-pony.com/disndat/calgarycraftsales.php
Most of the tables at different sales cost about $30-40, but occasionally you can find ones that are $20-25...but maybe you can find a friend to share one with you too.
I hope to have a booth at the Stampede some day too, but the cost is too expensive for me right now. They also usually want a percentage of profits as well. Good luck and hope this helps!
BTW, have you heard about the Etsy Alberta Street Team? People under the age of 18 can use Etsy to sell, but their terms of of use say that it requires the "conjunction with and under the supervision of a parent or legal guardian. In this case, the adult is the user and is responsible for any and all activities." (whew, had to add that in there).