Depends on whether or not I'm single, where I live, and so on.
If I'm living in the DC area with a couple of kids, then well over $100,000. (Try getting a decent house within an hour's drive of the city for under $400,000 or so, even now, and it could be difficult) If I'm unmarried, young, and living a bit farther away, like I am now, then $50,000 would be more than enough for me. (Although I'd certainly take more if I could without substantially impacting my quality of life) It's pretty context dependent.