I'm currently trying to breed medaka fry.
I use a syringe to collect the eggs and drop them into a breeding net in the same tank. The adults eagerly try to eat the fry through the barrier. My experience is very limited, but I'm guessing you could raise a couple of fry for fun in a tank heavily planted with dense things like blobs of moss. I don't think they'd breed high numbers without active intervention though.
Since my oldest fry is still very small, I can't speak to tank space overall. It's looking to me like fry would need to be at least 4 months old before they can live with the adults.
As for resale value. My LFS sells rice fish, so maybe yours would, too. And, really, I guess almost any species can be used as feeder fish if need be.