Yes, it is safe to buy new birds. But be sure to practice proper biosecurity measures and ask the right questions. If the breeder is honest, he will tell you up front what diseases he's dealt with. I always ask people that before I buy birds, none are offended but I have had one lie to me (as soon as the bird got home it became very sick with Coryza, it was isolated before it came onto my property and sent back to the lieing *choice word that's not child friendly lol*). I actually post my flock's disease history on my website. Take a good look at his setup and the condition of his birds. If his breeders are healthy and shiny, that's always a good sign, and if the coop is well maintained that's awesome too. Keep an eye open for wild birds in his coop and other pests that can spread disease. Ask if he shows his birds, and use common sense. You always take a risk bringing in new birds. Be sure to isolate the birds for two weeks, then offer up one, ideally two, "sacrificial birds." Don't literally sacrifice them, lol, but place them with your new birds for two weeks. If they get sick, you know the new birds were a carrier of some disease.