If you are looking to reduce feed costs, I would first check how much they are wasting.
A rough rule of thumb is that adult hens need about 1/4 pound of feed per day. So 6 adult hens would need 1 1/2 pounds per day, meaning a 50 pound bag would last about a month. Young chicks eat less than adult hens, but their appetites grow quickly. If they are going through very much more than 50 pounds per month, at any age, I would start by looking for spilled feed or feed-eating rodents.
As regards spilled/wasted feed, sometimes a different feeder helps, or moving the feeder to a new spot every few days so they can more easily pick up the spilled bits.
As regards free ranging, it might let them find some of their own feed, but you are quite right that predators could be a problem. Fencing a large area for the chickens may cost more than any amount of feed savings.
Chickens can eat some amount of table scraps, and enjoy scratching through compost piles looking for bugs. If you already collect things for composting, you might consider putting them in the chicken run to compost there, which also lets the chickens eat any bits they find appetizing. Chickens are fairly good at recognizing what is good to eat and what is not (not perfect, but good enough to keep them safe most of the time.)
For any suggestion about "saving" money by feeding something else, do check how much it will cost. Many things are cheap in one area and expensive in another, so they only save money for people who live in certain areas. And of course chickens still need correct nutrition, so tricks like adding water to their feed does not change how many pounds of feed they need to eat. (Nothing wrong with seving wet feed, and the chickens often like it. It may even reduce spilling & wastage, which really would save money. But it does not have any more food value wet than it did when it was dry.)
