Here's a site which mixes the list of GPU performance along with some real-world averages to figure out how much you can net per day...
http://bitminer.info/
This is a per card estimate, so you can use multiple cards in the same computer, or going further multiple computers. Once you start scaling into the hundreds of watts heat and noise is going to be a problem.
It's also closely tied to the market value of bitcoin and other variable factors so you can't simply say "if I buy a card that nets me $20 a day I will make $7300 in a year"