I heard about this recently and just came back from the super market. My local Wegmans which has a special section in the organic/natural area for GF products. Didn't find it there but had to go to the regular baking item aisle for Corn starch and White rice flour (they are still out of white rice flour, ugg!). As I was leaving the aisle I remembered reading that a national brand name had started making GF mixes. I didn't remember which one and just glanced quickly over the selection.
It was on the shelf just above the bottom, on the very end and almost hidden, but the Gluten free was big on the box so it caught even my bad eyes.
I grabbed a white cake mix and a brownie mix for $3.99 each (only 2c more than at Amazon and no shipping to pay). Cheaper than Cherrybrook or Pamela's so I figured I'd give it a try.
I checked online as soon as I got home and at Amazon there are tons of great reviews, on the brownies at least, so I can't wait to try these, and they sound quicker and easier and least added ingredients than any bought mix I've had, so anxious to try, even though not organic. I also have a Pamela's brownie mix in the cupboard I finally broke down and bought a few weeks ago and haven't tried yet so will bake them back to back to compare. I'll freeze some of each so I can bake them fairly close together.
I'll let you know what I think. If I remember correctly they are Kof K Kosher.
Meanwhile take a look at the reviews here