I feel a bird flipper may be spotted by how much they care for the bird as well as the amount they're asking. I know Rosie wasn't a flipped bird. my friends got her from a lady out front of a pet store for free, all the lady told them was that her husband was going to kill the bird that my friend named Rosie and gave no other info.
Kenji's old parronts were wonderful, they invited me to their home to first meet him, and had several people(different times) come so they had options. Although their add said a $500 adoption fee they never once mentioned it, and in the end said any money I would have used should go to spoiling Kenji. We talked about our favourite bird store, and also the vet since we both loved the same avian vet. They wanted to transport Kenji to my house and help him get settled in, I loved that! I got to show them were his cage would be located after quarantine, and they also got to meet Rosie.
A person adopting out a bird should care about the bird, not ask the price for a baby of that species, and truly care about the birds well being. I believe a flipper would ask for more money, possibly change their story, and not have the bird be their first priority. Push to meet in person, see the environment the bird is coming from, and if you have any suspicious feelings don't let them know were you live.