I recommend South Mountain Repitiles. I have purchased from them and Don is a pleasure to work with.
http://www.cornsnakes.net/
Serpen co has an excellant reputation and fine snakes. I have not purchased from Rich, but I will eventually
http://www.serpen co.com/shop/customer/
(Note you need to remove the space from serpen and co in the web addy for it to work.
Kathy Love at Cornutopia is another dealer with an excellant reputation. Check out her web site at
http://www.corn-utopia.com/
Finally, I have found two more breaders that look promising. Please check out Corn Snake Morphs and Creatures of the Night;
http://www.cornsnakemorphs.com/index.html
http://www.creaturesofthenight.com/