Ken,

I have no experience with Canada, but recently bought my first glider (partnered with 2 others). Two things I wish I had paid more attention to:
-Make sure the bill of sale includes mention of the trailer, and how much it is valued at, or get a separate bill of sale for the trailer.
-Trailers in US are often Titled in the state they are registered. It can be a headache to Title (and get license plates for) a trailer that does not have a Title. I don't know what Canada does, but try to get as official a document as possible for the trailer as is available, but at minimum a bill of sale listing the trailer and its cost.

You might also make sure you get a Title or similar Canada document for the glider, if any such thing is available. Proving transfer of ownership is a big deal. In the US aircraft are simply registerd with FAA and generally not Titled, as near as I can tell.

Rich L.