I have fed my p's earth worms and crickets from my yard ever since I got them. I was to stupid to know there was a 'risk'. But, regardless I have been feeding them worms and insects from my yard for along time with no issues.
Risk of parasites and toxic chemicals, yes? But it hasn't caused any problems yet and they're definitely cheaper than any other pirahna food.
Besides - you have to admit - anytime you see a living animal that will fit in your tank you atleast briefly consider making it into p-food.