I've been having luck lately finding brand name rotary cutters in dollar and surplus stores.
Last week I was in a "army" surplus store that also has a craft aisle (I think so ladies will go into the store) and found Fiskars rotary cutters on for 4.99. They were basic handles with a blade, but the handle had a pretty pattern on it and the Name of a 'artist line'. Kind of like buying a "Martha Stewart" branded item instead of a plain one.
So, I bought 3. One can never have too many backups. Right?