It varies quite a lot from neighbourhood to neighbourhood, and of course proximity to major public transport ingress/egress points.
I haven't looked recently, but I think you'd be hard pressed to find anything below $1000/month that wasn't out in the middle of nowhere.
Also: beware. Some basement apartments aren't actually legal; make sure you sign a legitimate lease agreement, and get confirmation from the landlord that the unit is up to code with the housing board. Happened to a friend of mine not very long ago.
