Thanks to Craigslist, I'm well on my way to furnishing the future office. So far, we scored a very simple writing desk for $10 and a 5'6" long, 30" tall bookcase for $25.
Now I'm looking for one more bookcase, a bench or pew, and headboard. After that, a media cabinet/TV stand should wrap it up.
I don't see myself ever wheeling-and-dealing for used mattresses or a second-hand La-Z-Boy. But right now, it's hard to imagine paying full price for a bookcase or table ever again.