I have purchased whole bolts of Moda Bella solids or Kona Cotton solids - usually I buy them while on they are on sale or with a coupon but usually you get a price break for buying in bulk. A few places to check are:
www.fatquartershop.com;
www.fabric.com;
www.greenfairyquilts.com . Greenfairy quilts usually has the best price on bolts of fabric and they have free shipping. Good luck.