Generally, you won't find truly quality breeders at a bird fair.
A good breeder would never put it's babies, and the rest of their birds, <breeding stock/pets> at risk for disease, which are very present at bird fairs.
I know of two breeders in my area that do attend the fairs, but neither bring birds, one breeder has a bird only store and they go to the shows to sell merchandise. They often have pics. of the babies available, but the birds are not available to purchase at the fair.
The other breeder has a computer set up showing videos of the babies available and the parents, but again, no babies available to purchase as the show.
Mostly, what I see at bird fairs/shows are lots of "backyard/hobby" breeders .. focus being on the smaller birds .. budgies/keets, tiels, quakers .. etc. I really have issues with most of these people, as you can just tell the birds are nothing more than $$$ .. they just want to sell, and really don't care to whom. Not to mention, with so many of these smaller birds flooding CL/Kijiji/Hoobly/Rescues .. etc. for rehome, it makes me sick to my stomach that there are breeders still breeding so many of them.
I did purchase a bird from a fair once, it was a huge impulse purchase, I got lucky and the bird was healthy .. but I will never, never again take that chance and bring home a bird from a fair again.