MKrauter, Steve Lewis (Doppler) is a very respected instructor and has invited you to contact him.
Bob Sherwood is also very respected and was just in Toronto doing Fundies last weekend. He has a group in Brockville, Ontario this coming long weekend. It's possibly a Fundies course, but I'm not sure. You could contact him if you're interested in joining them on that date or another.
Steve Blanchard is based in Ottawa, but that seems pretty far for you.
I'm not sure what happened to Dan Mackay that used to teach in Kingston sometimes. I think he's just in the States now.
There are LOTS of GUE mentors available in Ontario. If you post in the Ontario Diving Forum at
http://www.OntarioDiving.com you will have no shortage of GUE divers to dive with and help you in all aspects of diving. Divers, many of them GUE, post frequently on OD looking for buddies and love to help new divers.
On Facebook, there is a group called Toronto Area Underwater Explorers at
http://www.facebook.com/#!/groups/TAUEGUE/?bookmark_t=group, which is a group that was created for people in the Toronto-ish area who are GUE or who are interested in GUE. Many of the same people are in the TAUE group and post their upcoming dives often. You can join and post looking for buddies/mentors as well.
I'm not GUE and can't help you, but I know MANY GUE divers and a few GUE instructors in Ontario, and it's a huge community. Once you find them, and probably not at the dive shop you're currently with, you'll see that it's actually a pretty mainstream community around here.