I got the data on how much is required to buy a home in each state from from HowMuch.Net, Their analysis uses home price data from Zillow from April 2018, and then Zillow’s mortgage calculator to figure out monthly payments.
I got the median income data from the Bureau of The Census. The median income data is from 2016 but I used income growth from the FED to update to April 2018 values (approximated)
I simply did the math for each state to get the difference.
I made the final map using QGIS.