If your income is non-taxable, such as SSDI, VA Disability, etc. then it can be grossed up by 125% for qualifying purposes. So $13,000/year = $16,260/year to qualify.
How do I know your income may be non-taxable? Because you explained that it was fixed income at http://www.trulia.com/voices/Financing/relocating_to_mount_j
Anyway that $16,260 breaks down to $1,353/mo. I am not sure how your credit is, I will assume it's excellent, and I will assume a 4.75% 30-year fixed rate. I will also assume that the property taxes would be $1,250/year and that insurance would be $720/year, and that you are buying a home that has no condo or homeowners association fees. With those assumptions, that would put your debt to income ratio at 42.978% which would qualify for pretty much nearly all types of mortgage financing.
If your income is taxable, then that would push everything up to about 53-54% debt ratio and that is tougher for underwriters to approve.
Let me know if you need help.