You can add TOO much manure to a garden...
There's a lot to consider. We've had 5-7 for a few years now. It's definitely nice to have a steady supply of eggs with six kids in the house. And it's not a ton of work, once you get things set up. Our setup is janky but works and a lot was done manually. We get the eggs, free food waste disposals, and compost for the gardens.
That said, if you're strictly going into it to save on eggs (or just to have better eggs), you're better off browsing local forums to find someone nearby who's up and running, IMO. They can work if you're doing a whole homesteading thing. Just by themselves you're at best breaking even with feed and time.