Your profile says that you live in Ohio. My advice would be to go to the Lucasville show (Southern Ohio Poultry Breeders) October 6th and 7th. It is the APA National meet and there will be many breeders there with birds to sell and to take orders.
Next you might try the Columbus show (Ohio Poultry Breeders) in November. This is by far the largest annual poultry show in the nation and top breeders from around the country will be there. Hundreds of birds are bought and sold there every year.
Also, you need to let breeders know if you want large fowl or bantams.
If you are looking for Standard SC White Leghorns I will have a pair of hens for sale at Lucasville that would make excellent breeders.