Yes I flip bikes. All my bikes are pieced together from bikes that I have flipped. I dont like spending money for bike parts. If I can buy a bike and harvest the wheels, or cranks, or saddle, and sell off the rest and break even, I'm happy. If I make a few dollars, even happier.
To flip bikes and make money thats another story. In Chicago bikes sell very cheap. I've found its just not worth the effort unless the bikes I am selling were acquired for free or very little money.
Now that its winter though, I'll start searching a few out to repair and repaint just for the fun of it. I make no money on a repaint, but I have the satisfaction of bringing a bike back to life and making it look good.