Don't buy just to build stash--big mistake. In time you will really know what you like and will use. Recently I was at a sale where the quilter was so busy buying patterns and all fabric to go with it she never really had time to enjoy the piecing and quilting.
she has so much she had to sell most of it for the room in house. I bought a $175.00 kit for $50.00. The girl took a great loss selling her good quility fabrics for $4.00 yd. She just got caught up in buying stash.
I don't think having a stash is very important because there are many places to shop when needed.