I personally don't waste time with Joan and her turnips. There are much better ways to make bells in this game. The island is enough for most players, but I use Re-Tail as my own personal Gem Shop as a side business for nice amounts of day-today cash. I sell 3-5 gems and nuggets per day for 7-10K each. Those are very nice profit margins. But, to each their own - some like the whole Turnip process. I personally don't have the patience and feel that the return isn't worth the effort.