These breeders are long established and well known for African species.
Old World's price list surprised me, his prices seem low (which is a good thing). Not sure if it's the current prices, but this is the link found from Google.
Old World Aviaries - Hand-fed baby parrots
Jean Pattison is very well known in aviculture and has been considered a leading authority on African parrots for decades. I don't know if that's why she feels she can justify "above average" prices for the same species as Old World?
African Queen Aviaries
Also, if you look on birdbreeders.com you can find more breeders. After calling and speaking with someone, it should be apparent if they "know" their stuff. Ask if the birds are fully weaned before going home, abundance weaned (onto variety of foods at the babies own pace), do they let their babies fledge (learn to fly) before the option of wing clipping, what precautions do they take to reduce avian contagious illnesses including deadly viruses from entering their aviary? These questions (what I can think of off the top of my head), plus basic chit chat with the breeder should give you a feel of whether this is someone you feel comfortable doing business with.
My Robin came from a bird store 21+ years ago

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