Detroit (and every other ghetto inner city) after the burst had HUNDREDS of houses in the $100-1000 range.

This only assumes that the house is both livable and that a person would incur absolutely NO costs of moving to said location. Yes if you infinitely move the goalposts using magic that isn't how the real world works you can potentially make up situations where it is possible, but that isn't what the discussion is generally about.

Also can you introduce me to a bank that is approving a mortgage for $2 a month? I'll wait.

Because as someone that worked for a bank, this mortgage does not exist. Not enough profit to justify the mortgage. So someone with a job is not able to afford a $2 a month mortgage simply because those mortgages do not exist.