Check out ghost shrimp. There are very cheap, no more than $0.50 a piece and are natural to the ocean and fresh water. Working at a LFS For many years, I loved feeding these shrimps to all the preditors, it was just like my diving expierances seeing fish act like wild fish.
Downside, they wont provide the best nutrition and you will have to continue to give other foods
Downside, IME once you get a fish/eel hooked on live food again, it is hard almost impossible to get them back on frozen and friez dreid.
Also, do a search on the mollies, I remember someone in the new hobbiest posted a thread with succeful breading in saltwater.