[maple_leaf_eh]

One of the more active buy/sell "theatres" in Canada is Kijiji. The country is broken down by province and then by city or region. If you set up some structured queries (and save them as text files), it is easy to run searches every day. If there is an alerts tool, I haven't found it.

The other possible source would be the truck and heavy equipment trader websites. The electronic versions of the paper copies seem to get a lot of traffic.

Of course, finding one is only half the job. Then you will have to identify what is actually offered and negotiate with the seller. Recovery and transport are another set of issues.