I see that you live in texas. At one point in my past I was on the brink of moving there and I had a chance to review property prices and you can buy a pretty decent house even with a $25k salary depending on the liabilities on his credit report. It's possible with some reserves you could afford a 100k home, less depending on what's on his credit report, if anything.
You'll need to speak with a lender to determine exactly what he'll qualify for as the automated underwriting engine that all lenders use will give you an absolute answer with the appropriate documentation provided to the lender.
Don is correct. Most lenders require a 620 or even a 640 now from what I've been hearing from other lenders.
I almost forgot, if you're looking to buy a mulit-family home (2-4 units) then your buying power will go up and you may qualify for a lot more home than you thought possible.