a few more suggestions...
You might also look to see if there are any reputible reptile shops in your area. There are a couple very close to me. If you aren't sure how good the shop is, go to it and use your eyes and nose to tell you a few things... does the place smell bad? are there bugs on the animals, dirty cages, are the water bowls clean and full? What are the employees doing (talking on the phone to a buddy or cleaning cages/helping customers?).
Also, if you can contact your local reptile club (if you have one) there might be a member who breeds corns locally. This person may even sell some of his corns to local pet shops. I have bought a few really nice corns at the local all animal pet shop that were bred by a member of the club I belong to. As it's a nice shop, I had no problem paying the little extra I had to pay to get them through the shop (overhead v/s direct from the breeder)-they were still pretty inexpensive. Not are pet shops are evil!
Look in the newspaper. There are lots of people breeding pretty nice corn snakes in my area-it may be the same for you. Unless you are looking for something really high end, you may find something pretty close to home.
Good luck!