Keep your eye on the Calgary Buy & Sell and the Calgary Craigslist. There are often people selling them privately for a good price.
Princess Auto, of all places, was selling used ones (in great shape) for $25, but I don't think they have any left.
If all else fails, I have heard good things about this guy: richard.whittaker+kegs@gmail.com who is selling off a bunch of them.
You will probably need to recondition them yourself, which is very easy (you just replace the seals, which can be purchased at The Vineyard south, or lots of online retailers).