Most fabric stores have end of bolts and clearance fabric. I wouldn't buy precuts unless it had each fabric from the designer line. That's the main advantage of buying precuts. You have to be sure the precuts would not bleed, you don't pre wash pre cuts. If the fabric you will be selling is not good quality it doesn't matter how cheap it is and how cheap can you sell good quality that others aren't? If you can then you have a start of a great business.