Personally, I think it is nuts to think you have to buy fabric and have a stash. Most of us have left over fabrics, particularly those who make their own designs. I suppose if you only use patterns you can buy EXACTLY what you need, but that has drawbacks also. I have two plastic drawer sets with smaller fabric pieces sorted by color and I use them all the time for accents or medium or small design elements (no way would I cut them into squares... I need them in too many shapes)! My one cupboard 8'x4'x20" is a little more than half full of yards of fabric. Sometimes I buy fabric that is sooo beautiful and know I'll find a use for it. Often I buy more than enough for a single quilt so that I can use the fabric pieces in another quilt also. I do a lot of applique and that uses up a lot of my stash. I never have gone out and bought fabric just so I can have a stash. Stash happens; if you have to shop for it you are going to end up with too much and the wrong colors.
If you are new to quilting, don't buy to have it on hand; buy because the fabric calls to you, reminds you of your brother or grandchild, or..... because you absolutely love it. A quilting friend gave me some panels of a fabric which is the most beautiful that I've ever seen. I immediately used it and then realized it would also be perfect for another friend who is a part of our extended family, so I bought several yards before it became hard to get.
Having rows and rows of shelves with fabrics is something I couldn't handle. I've only been quilting for 10 years and there are some fabrics that I bought for kiddie quilts (I have 13 grandchildren) and other fabrics that I don't really like anymore, and have very little use for now and find myself doing church drive quilts for children and older people. Tastes evolve. Stash happens. Don't work at it, let it evolve and try to keep some control over your buying impulses.