Use to be monthly mortgage/rent should be 1/3 of your monthly gross pay.
The measure I use is that a year and a half out of college I bought a townhouse for 150% of my gross salary. Ten years later I bought a house, again for about 150% of my salary.
My daughter is four and a half years out of engineering school and homes in Dallas seem to start at around $450K. And, no, she is not making $300K..(Yet! )
nacl