I emailed WGBH Boston Home Video asking about the Sept 2006 release of Degrassi High. This is their response.
Thank you for your interest in WGBH. We always appreciate hearing from our viewers, listeners, and web site visitors.
The release of Degrassi High on DVD, originally slated for September 2006, has been tentatively rescheduled for a release in the Spring of 2007 due to production delays. It is subject to change so check back with us at WGBH Shop online at http://www.shop.wgbh.org for more detailed information.
Thank you very much for your patience!