I use the Kona prepared for dying fabric and the only place I was able to find it was Joann's on the website by the bolt.
I have used their other Kona cottons when I need a solid and have found no difference either with the quality between the LQS if they even have it or Joanns. I don't like a lot of the thinner ones that the LQS's carry, and those carry well known brand names.