I very much like the idea of selling my own goods in an afk shop, though I also like the idea to use NPCs. I'd accept a 10% sales tax as a good trade for not having to sell produce at the game's set price or hunt for a buyer.
By the way, why do the Food Stall and Chef Stock shopkeepers in Elvedin City sell exactly the same range of items from stalls facing each other? Seems a total waste of a shop. I'd like a shop that sold those food items you need for cooking, like garlic, which you need level 8 farming to grow. The food stall would seem the ideal place.