I'm not sure what you'd consider inexpensive in terms of french toast b/c most french toast is inexpensive. But, here's some past threads:
For suggestions in the Bronx, post on the Outer Boroughs board.
It's been a while since I've been there so I can't give you a price range, but most breakfast places tend to be rather cheap. Anyways, go to Sarabeth's on Central Park South, their Almond Crusted French Toast is amazing and it goes really well with their pork and apricot sausage.