I knew a couple in the 1990s living in a loft on the Lower East Side and only paying less than $300 per month. There was a tacit agreement that the landlord would not upgrade the water, electric, and heating systems to legal code and would not issue keys, but the people who lived there could keep paying around 10% of market rate to live there. They and other residents bought padlocks for their front doors and got in and out by unlocking the padlocks. They brought in space heaters. They did have running water and electricity, but the pipes and wires were old and likely dangerous. If the landlord had had enough money to bring the building up to code he could have charged 10 times more per month. They had been living there for 19 years. No idea what’s happened to them since then.