Try asking in the northern garden forum for referrals. You will need to search for a nursery closer to your location the reason is you need to ensure the plants you get is hardy to your area. Sometimes trees are grafted onto hardier stocks which makes it seem as if they've gotten hardier in that zone. Or it may be that the climate is warmiing up and more plants are able to survive in zones lower. For example, I was surprised by the proliferation of japanese maple trees in my zone which is a zone 5 or a US zone 4. I later discovered that many were grafted. Same thing with David Austen Roses.

Try this nursery. They have a very extensive list of plants.
www.whistlinggardens.ca They are located in Ontario.

Yugoslava

That whistlinggardens.ca centre sure looks an interesting place to have a look at

Emailed to see if they are yet open

Try Gardens North. I purchased seed from her in 2007.

Thanks all for their suggestions, you have given me some good leads and I apreciate it :)

Terry