It is a quick rule of thumb, after that, get you calculators out. If rental income is $1,000 a month, you would pay $100,000 for the property. Has worked well for me for quick analysis.
We just cashed out of the VA suburbs of D.C. Our rent is $2000 a month and there are 2 empty (brand new) homes next door for $600K and $650K. The financing fell through one one. Don't know the story about the other one.