My brother used to have a turtle, and he feeds it with something like the ones given for fish. Unfortunately my father thought it was dead one time and decided to throw it.
My son is wanting a turtle but so far we have not bought him one he loves animals he wants about every animal that you can think of even a SNAKE I told him there is no way that he is going to be getting a snake I hate those things...
I used to have two small turtles. I just kept them in a round bowl aquarium. They're not hard to maintain, you'll just have to change the water often if you don't have a filter, cause it will stink. I also fed them with dried fish, which is very cheap.