I'm a bargain hunter, too. Our LQS's are 9.95/yd and up -- so I've stayed away. By offering lower prices, you entice more customers into your shop to take advantage of the "bargains" and perhaps complement the grouping with some of the regular priced fabric. I'll go back to a shop if I know they sometimes have bargains. If they run just straight line prices, I usually stay away. As for "new" lines -- today's new lines are tomorrow's old ones. My quilts may be new, but the fabric in them sure isn't.
I would think the challenge is to entice people into your shop first. You will naturally get more repeat customers if you offer a variety of prices. And what you don't get in profit from the older lines, I'm sure you will make up in notions, patterns, etc. that are purchased for use with the less expensive fabric. When a customer perceives a bargain, excitement sets in and the plastic card comes out. It's all about the thrill of the hunt.