The lack of a readily available IPA that's brewed in Ontario seems more & more odd as the years pass.
I can walk into a BC Liquor store and find at least half a dozen (sometimes a dozen) different ones:
http://www.bartowel.com/?p=1939
The Magnotta True North is more of a British version... it's too bad their West-Coast IPA never got widespread.
Great Lakes often have Project-X bottles for sale on-site. They've won the last couple of Ontario IPA challenges at Volo.
Amsterdam occasionally has their Boneshaker on-site as well.
If you're near the Granite, growlers of their Hopping Mad are a great value.
But yeah, if you're outside the GTA, it's pretty tough. It's great that the Grand River was more widespread this year.
You might also consider Flying Monkey's Netherworld Cascadian Dark Ale. The last pack I had wasn't even that dark. It's not overly bitter, but it's loaded with fresh hop flavour.