You may want to look into online swapping sites. One site I've been a member of (no longer, though) is Swapbot.com. They have ongoing swaps for fabric by color, size, shape, or ready-made blocks and projects. One you might find helpful is called the stash builder swap. Each month is a different color-- you purchase one yard of two fabrics in that color family and cut it into fat quarters. You keep one and send the others to three partners who each send you two also. Pretty soon, you have a nice collection of FQs in lots of colors to pull from. It's free to join Swapbot, too!
meg