Another option (if you don't want them shipped) is going to reptile expos. Breeders from all over gather to sell their snakes.

Repticon has three in your state: one in Columbia (it's coming in July so not too far away), one in Greenville, and one in Charleston. There may be some smaller expos near you as well. If you go to Kingsnake.com and click on "events" it will show you all the local shows. Shows are a great place to meet new breeders and even seen snakes in person.