A couple of other places on the web for rotary blades: www.sewingpalace.com they have 45mm blades, 5 for $12.95 with free shipping.
www.southstarsupply.com 10 pk of 45mm for $17.95
I did order some from Harbor Freight yesterday after going to Joann's & getting a 2pk for $6. (that was with my 40% off!)