Showing chickens isn't really about buying someone's stock and putting it in the show. . . Unless you want to pay big $$ for an adult bird proven in the showring, you're going to have to start with a large batch and, umm, cull? down to your chosen bird in order to have success.
People who show poultry are also people who breed them. The big point often in showing is that you allow others to see what work you've done on your birds to get them to that state of perfection.
That being said, you need to specify what breed you want to show. Showing is about loving a certain breed. Once you have a breed named, it will be a lot easier to get breeders' names.
I raise Blue Wheaten Ameraucana as well as Blue and Splash English type Orpingtons.
I have never shown my birds nor do I plan to, it's just not my thing. However I have acquired stock from highly respected breeders within the given breeds and then like Illia mentioned, culled down my stock to a level that I think is acceptable for breeding quality birds.