All large hatcheries sell started pullets. But, availability is hard to find this year. You can go to a livestock auction, but can come away with good birds or sick or old birds. Some people label the birds at auctions, others do not. We’ve sold several healthy pullets at auction, and some hens. No issues, just we had others we preferred.
you can look for farm pages on fb that are near you - cannot sell animals on fb, but you might find a farm with available chickens. Going into winter, some people naturally thin their flocks, so you might find some good choices. Understand though, that whatever you buy (other than a known age young pullet from a hatchery) will likely molt this fall or winter.
