I think I can help you. Since I don't have much money to spend on the frozen food food for fish from the pet store. I did research about food and I have few food I can find around the house you can feed your fish.
* hard boiled egg( this can be messy since they become some fine particles after hit the water but my tetras and cory would like it. I usually feed it after it dried up and hardened a bit, so it won't fall a part as much)
* beef heart mix(you can find the receipe on the web. And you can make home made frozen mix food. And keep in the freezer. And my fish love it.)
* most of the unseasoned cooked meat(chicken, beef and pork. Just chopped them up to the size little smaller than their mouth)
* most of the seafood(again unseasoned cooked or raw. fish fillet, shrimp, clams etc)
* cultured live food(like grindel, white, micro, and earthworm. vinegar eels, daphnia, mosquito lava Fish really love them live food. After all it is their natural food which move. Just make sure you either culture them or collect from the safe clean uncontaminated place)
Culture food may require some time but it cost so little to maintain. And some may improve the fish color.