"Four in 10 adults in 2017 would either borrow, sell something, or not be able pay if faced with a $400 emergency expense." https://www.federalreserve.gov/publications/files/2017-repor..., page 21. That's a lump sum expense, not paid over time, but I think it illustrates quite well that $370 is a lot of money for something most people don't even know they need.