My mom and I have about 15 snakes. And some of them, mainly ball pythons, have refused, for ten years straight, to go to prekilled. So breeding live mice is kinda the cheaper option. As well, when my sand boas drop a litter or two, they much prefer live to prekilled pinkies (I read that it is actually better for their first two or three meals to be live). Far easier to breed my own, though I do admit we have dedicated the spare bedroom to being the mouse room, and every week it takes me about an hour to do maintenance and cleaning on teh 10 gallon and 20 gallon long tanks, as well as lab cages.
Our mice do have it good, unless they are babykillers, and then no matter how pretty they are, or advanced in pregnancy, they are snake chow. We've pretty much bred out the kill-babies-humans-touch-them mice and even though we rarely handle them, the mice are docile and can be handled easily, unlike the ones I've seen in pet stores. Who knows.
as well, when our snakekeeping neighbors need a live mouse, we always have one or two to spare. We recently got into natal rats, and those guys are great as ball python food.
Funny thing: a natal rat raised by its parents is jumpy. a rat raised by our mice is calm and will even take care of the pinky mice in its cage. Natal rats have great maternal instinct too, and readily take pinky mice when offered and add them to the baby pile.