Bitcoin mining - hows the payout?

So in one of my other threads I made a post about how I want to build a high end PC and one of the reasons was to bitcoin mine. Now the interesting part with me is that I rent an apartment and I'm grandfathered in with hydro so my rent doesn't fluctuate based on consumption. For obvious reasons when people talk about how much they can potentially make they factor in electricity. Well in my case I wouldn't have to factor that in so are we talking $12/day perhaps?