I get generics on ebay. I'm very happy with them, but they cost $1/blade. $20 is a fabulous deal. Just make sure that they are the size you need 45mm??. I know on ebay the 28mm are less expensive.
OK, just looked at the ad. The blades are $169 for 100. THEN they would throw in the Olfa handle which has a Retail Price of $20.95. It's not $20.95 for the blades & handle.
Scroll down to see ad and read carefully:
http://jhittlesewing.funoverload.com...temid=070915m1