In both stores I go to they are in the first row of shelving just next to the registers. Mine happen to be 2 to 3 rows from the right of the store. From the front of the store walk up the isles and at the end of that isle they are up to the right. Sometimes they are hard to find just keep looking if the staff have no idea what you are talking about. The handles of the carpet cutting blades are yellow and the package of blades are yellow with a red stripe.
Here is a pick of the handle to help you find it better.
http://www.harborfreight.com/catalog...+cutter+blades