It all depends on your situation. When you say that your GF "should" make 30k out of college, that right there says you "should" take her income out of the equation. Never focus on anything that isn't reasonably certain.
For me, it is a matter of where you are at in life. Are you looking to get out of an apartment? Are you looking for a place to raise kids? Are you looking for what could potentially be the last home you'll ever live in?
If you're looking to get out of an apartment, you'd be better off heeding the advice of some in here and getting a modest place well below what those calculators suggest you should be able to do. If you're pulling in 50k solely, and there is no guarantee that your GF is going to be legally required to make payments on the house, you should figure with that income and your expenses alone.
Then, at 50k, you figure that you should be able to cover a monthly mortgage (tax and insurance included) bill with one bi-weekly paycheck. I'd say you'd be more realistically looking at no more than 200k, and probably less than 180k. You must also take into consideration your vehicle situation. Are you a car loan/lease kinda guy, or a buy it with cash kinda guy? Then you should consider the age of the house and its current condition. If relatively new and in good shape, just plan on having 3-5k available for any surprise expenses. If older and in need of repair, you might consider doubling that amount available.
There are a lot of variables to consider. But it all depends on how you choose to spend your remaining income. If you go out to eat often, have high car payments, etc., you'll want to go a lot lower than what you can "afford." And if this is going to be a house you have for 3-5 years, you should consider buying a fixer upper (not too broken down mind you) to help you learn the ways of home ownership/repair.