Somebody once told me to add $100 to your monthly payment (if you're financing) to budget for repairs, upgrades, etc. throughout the year, plus another $50-100 if the vehicle's fuel economy sucks (which ours obviously does). Use that basic formula to figure out what you can afford per month, then do the reverse calculation to determine what the maximum purchase price you can afford would be (if you have good credit, assume an 8% APR across 60 months to be conservative). Then you start looking at VX's in that basic range, while also doing the additional research to determine what a reasonable asking price would be for each vehicle you're considering.