The program I worked for was about $900 a month. When I did the program (in the 90s) it was $500. In addition, the policy was to not turn anyone away, even if they couldn't afford it. So there are options out there. It was a non-profit program, but received very little government funding.
In addition, in the last decade a deal was made with Ontario Works -- A potential resident could claim the rehab as a residence and get OW. Of course, we would take that money for rent (still less than the monthly cost). It made rehab much more accessible, although I'm sure there are many right-wingnuts who would have had a bird if they knew their tax dollars were going to OW recipients in rehab.