Try
www.greekdancing.org, and go to the forum section. Lots of people on this forum really know their stuff when it comes to traditional dances and music - many are Greek Americans involved in traditional dance but there are also instructors from Greece and North America who are well respected within the dance community.
One good person to talk to would be Kyriako Moisidis, who goes by just Kyriako on the forum. He is holding his 8th annual seminar of Greek Dance on the island of Ammouliani, at Chalkidiki this July, and will teach dances from Evros (Thraki), Kioumous Maten and Kars (Pontos), East Chalkidiki and more. He or somebody on the forum will surely be able to help you with questions.