I plant a garden just for the chickens. It still gets taken care of but admittedly, it doesn't get weeded nearly as often as the regular garden. Everything I put in this garden is stuff I will feed the chickens. I buy cheap seeds or replant volunteer plants into this garden. I let a few of the lettuce plants go to seed so it re-seeds itself. I've gotten fresh lettuce crops all the way into fall that way. Occasionally I will let a few chickens in to peck and play. They usually do a number on the weeds and take a bite out of every tomato, but hey...it's their garden! Mostly I pick the veggies and dice them up to throw in the pens. This is a great way to get produce for chickens that aren't free ranged.
By buying the seeds on sale at the end of the season or just choosing the cheap ones at dollar stores, I save a ton of money over buying transplants. If I pay $.25 for a packet of tomato seeds and only a few germinate and grow, I will still get several pounds of feed from each plant. I could buy the name brand seeds like Burpee for $2-$4 a packet. Granted a higher percentage will probably germinate and grow, but I still only need a few plants of each per year. That means the rest of the seeds in the packet are waiting till next year where you're now getting germination rates similar to the sale priced seeds...except the original cost was higher. I'd rather spend the same money on a variety of seeds and maybe try a few new things while I'm at it.
By using discount seeds and with minimal work, a chicken garden is a great feed bill money saver!