$32,400 a year. If social security you can multiply by 1.25 I hear)
$40,500 a year credited ( no taxes) income x 3 = safe mortgage. about $121,500 loan.
Now for the problem. 500 fico is so low you will not get a loan (right lenders?)
What you want to do is to talk to a lender or non-profit counseling service. Do not consolidate your loans. That will only drive your score lower. Find out what if anything you can do to increase your score. Take some time, get it up, then you can buy.
You have 2 other options. Both hard to find. rent to own, and lease to own. Find someone who wants to sell so badly (and has the house paid off) that they will sell it to you financing the whole deal them-self.
You may be able to find a hard money lender who would finance you. But their interest rates would eat you alive. You would be a lot better off to work on your fico score to improve it. Then in 1-5 years with good credit buy what you can afford.