The absolute first thing you're gonna need to do is get a licence...which will require a test/course for a first-timer. THEN, the frustration begins !!
Personally, I never had too much success at trapping coyotes but snaring them is another story. I didn't hang any snares this winter but my all time high for 1 year is 110.
And to answer your original question, traps can be purchased at Halford Hide or the Alberta Trappers Ass'n. store in Westlock.