When you can't close the door to your sewing room and the floor is sagging from the weight! For me I think it is a balance between having enough to be able to shop your stash and satisfying the need to buy.
BTW, ArloJo, what quilt shops did you visit? I used to live in Tacoma, but that was before I took up quilting. I'm hoping to visit my family in the Tacoma/Seattle area sometime this summer and would love to visit some quilt shops.