I get my birds from
TSC, who get their birds from a hatchery. In this area of the country, that's Hoover. Our local Ace Hardware also gets birds, more expensive, unknown hatchery, appear to be similar quality. We also have Rural King, whom I understand uses Cackle for their supplier, I just need to drive across state lines to buy from them (not a problem, just a difference between FL and AL in terms of who dominates the farm store market in the area).
Regarding Hoover's birds, they are adequate. Won't win any awards. In no way superior examples of the breed - in fact, what they sell lots of aren't breeds at all, but rather brand names they've put on their own, effectively, landraces of mixed chicks.
TSC itself does little to train employees, and the employees in my area do little on their own to learn. Add the involvement of the USPS, and you have a buying experience NOTORIOUS for misidentifying birds. But if you want Comets, or CornishX, or Pekin Ducks, they are cheap, readily available, and will provide meet or eggs as expected.
In fact, I have one of their CornishX hens, laying eggs right now, at 11.3# and 36+ weeks of age. She was light at culling age, I'm hoping to get some chicks out of her to mix with others. I've a "project" going, search for "Lemonade". Three of their Comets have been very reliable layers, and now mass out at 4.9#, similar age - that's heavy for a Comet, and they seem healthy, happy.
If your plan is to breed or show, I would not recommend sourcing there. Eating? Fine choice for small flocks.