I used puppyfind.com last year to sell some of my pups and all worked out well. Luckily the buyers that contacted me and I sold to lived in my close area and they came to my home to meet me. I did have some weird emails from Greece and another one out of country that wanted a broker to pick up the pup, but they would send me all the money up front. I said No! I do not sell to brokers and must meet the buyers before I agree to sell my babies. I want to make sure they get a great home. And I feel that anyone sending a broker to pick up a pup - doesn't really care that much for the puppy. So no way!
Just screen the sellers. If they are rep. they won't mind giving you their vets name or references. You can also check with AKC list if their still able to register with them or not. We have a link somewhere in YT to check if they are not rep. breeders. Best of Luck!
T.