As I mentioned I have a Sharpener, and after owning one I'd never want to be without it. I feel like saying send me your dull blades and I'll make them sharp again. There's no point in throwing something good away. And yes they are at least $7.50 for a single at Joann's and that was a couple of months ago. It's much better to get a deal on several like you all are talking about.
My Sharpener is made by Colonial and says "Dual Rotary Blade Sharpener" Hancocks has it for $9.98 right now
http://www.hancocks-paducah.com/Item--i-TS-45, but you can also get it from
http://overstock.com for $14, I'm not certain which would be less after shipping.