Heh, I just got your subject line
Anyway, my local Petco will accept some fish as donations, which they will adopt out for no cost. This might be an option with fish shops near you.
Otherwise, you may want to find a school or university that might want them for classrooms or research.
Lastly, maybe you could find someone who wants to set up a new tank; you could provide them with a fish stock at little or no cost.
See the last subject at
http://faq.thekrib.com/breeding.html#raising