You just missed a sale on the Derby blades that ended 9/21 $9.99 for 100. Derby has a store on Ebay, go to Ebay stores and search for Derby. I picked up 100 blades for $17 shipped and they even threw in a tube of their shave cream with my order.
I already got 100 Derby's among other things from that store on Ebay, plus he chipped in a nice tube of lavender shave cream which I find invigorating.