Fabric can be divided into catagories: Basics and Trending.
Basics: These fabrics are exactly like the name implies, basic coordinates. Kona Solids, Moda Marbles, and RJR Handspray are examples of basics.
Trending Fabrics: These are collections with prints and colors in the latest style and current trends. Trending Fabrics are always a limited production run.
Why is this important? Basics are always re-orderable, and available, higher quality basics will have little or no deviation between production runs. Trending Fabrics have a life span, and you better get what you need while it's available. Flip side to that, is that you rarely see Basics at closeout prices or steep discounts, it is a fixed supply at a fixed price.
Trending Fabrics sometimes end up at deep discount if by the end of the product life cycle there is a lot of overage, the manufacturer will blow out the remaining yardage to recover what money they can from it, this brings me to our next to important concepts in fabric buying: Order vs. Speculation.
Production based on Orders: The manufacturer only produces as much of a new line as has been ordered. This is how Moda does it, which is why if a fabric shop does not order the collection a few months ahead of time the odds of that shop getting the collection after it is released is minimal at best.
Production based on Speculation: This is how most manufacturers produce fabric. Somebody decides how popular they think a line will be then produce based on that assumption. Some calculate this better than others, but this is where closeouts and bargains come from. When they miscalculate and over produce they drop the price to move it out and recover some of their investment.
Why am I telling you all this? An educated shopper is a better shopper. The real price of quality cotton fabric about 10 bucks a yard when you find quality fabric at about half that price, it is because somebody screwed up.