Many of our friends down south will not ship here.
Having said that, if you earn the respect and reputation as a formidable northern friend, you will find folks will down south who will bend over backwards to help you out, and eventually you'll have less difficulties.
Additionally, shipping up here is very costly, if you are looking for protection with tracking (which many do). A little grease goes a long way; try offering an extra 20-25 dollars on the deal to cover the burdens of shipping (assuming its worthwhile).
They also need to fill out forms etc, so unless you make things incredibly easy and packed with Canadian-niceness, it will simply be more convenient to deal with CONUS members.
The more people who have great experiences with Canadians, the more they open up.
Most ECF members are wise and protective when it comes to classified transactions. We are definitely "foreign" for many members, and our regulatory situation makes it difficult to be won over, rather than passed up.
Hope that helps.
PS. PMs are far better for building relationships than piping up in a
thread for classifie transactions, IMO.
Good luck!