The one thing I remember about camping in Ontario was being frustrated with their prices and permit system. At the time (2003 or so), I considered anything over $15 a night akin to highway robbery. Prices in the Provincial parks were something on the order of $25 a night at that time and too often the facilities were sub-par for the price. I thought we'd head into the backcountry to both look around and camp cheaply. Then I learned there was a per-person, per-night fee for non-Canadians to camp (dispersed) on crown lands. That meant I not only had to find a place to camp, I also had to go back to get a permit and specify where we were going to camp. We had to drive to a gas station or sporting goods store for the permit, then back to camp.
I guess my advice is to be sure to check into current policies, procedures, and prices for the area in detail before you get on the road to avoid surprises. I see at
http://www.ontario.ca/rural-and-north/camping-crown-land that you can now get a permit via email and the fee is a per-person-per-night fee of $9.35 plus tax. With the difference in US and Canadian dollars, perhaps that's not so bad after all (if you don't have kids). Then again, you'll need to figure out how you're going to get those emails.
Also- I see from other browsing that some canoe routes in Ontario require you to reserve where you'll stay each night and of course pay the fees.
As to the Temagami area specifically, I see that's where Grey Owl developed his Indian persona and, perhaps more importantly, his early ideas on conservation....
http://www.pastforward.ca/perspectives/august_112000.htm
http://en.wikipedia.org/wiki/Grey_Owl
http://www.northernontario.org/NorthernStories/GreyOwlJL.htm
Gee, I think I need to come up with a Grey Owl trip. Temagami (ON), Riding Mountain NP (M
, and go see his cabin at Prince Albert NP (SK)