Since you will probably have to clear customs, in the 4 hours doesn't leave you enough time to leave the airport.
If you don't want to eat in the airport, the Sheraton (across from T3) has a restaurant. I've never eaten there, but I'm sure the pricing is equivalent (or more) to the airport restaurants. You would have time to take the train there even if you are in T1.
Most of the restaurants are after customs. I can only think of food court types before. In T1, we normally eat a the Molson Pub. Not because it's cheap, but because it is pretty much the only sit-down restaurant. The food is acceptable.
As for T3 restaurants, it's been a while so I can't remember but I'm sure there is something along the lines of the Molson Pub there as well.