Charlotte Heath is a recipe vendor in the base camp of Celestia. She has several LVL 50 items but won't sell them to any of my LVL 50 wizards. The buy button is greyed out and on mouse-over it says grandmaster crafter only.
My wizards are level 50 grandmasters... What gives?
As you say, Charleotte sells Recipes, not items. I think the GrandMaster Crafter refers to a crafting level you must have, not the level of the character.
For example, when I go to page 15 of the Badges screen in my spellbook, I see that I am only a Master Artisan.
So, even though I have a Level 50 GrandMaster, my crafting level isn't high enough to buy the recipes yet.