Between rent, student loan payments, health insurance, bills, and car loans, and food, I think we maybe have $500 left to throw around each month. If we were paying against a mortgage, that would basically be zero.
The most financially effective way to be a programmer is to work remotely for someone who pays SF or NYC salaries and live in a moderate COL area.
I've always seen the rental income requirement you stated phrased as "monthly income must be at least 3x monthly rent", in case the 40x thing threw anyone else off (40/12=3.33).
I've recently seen 45x monthly in Manhattan and LIC (Queens).
And, as a sibling comment stated, it depends on location. I think $80k is right for most areas of the country. If you live in NYC, SF, LA, or another place with really high cost of living, adjust accordingly (which is probably like 2.3x).
You may not be able to afford a house in the area you want, but you can certainly afford a home. Here's one with a mortgage for $89/mo.
http://www.zillow.com/homedetails/207-1st-Ave-W-Gackle-ND-58...
Two people can easily live on $40-50k in most areas. Eliminate all the unnecessary expenses like $150+/m in phone payments, $50+/m for cable, etc.