I have the Olfa cutter, "ergonomically" correct. Here's a link:
http://www.olfa.com/RotaryCuttersList.aspx?C=2. If you have a JoAnn's or Hancock Fabrics near you, and are on their mailing list, you can use one of their coupons on it. Also, here is a link for getting replacement blades:
http://www.lpsharp.com/3.html, this company has excellent service.