This product is now manufactured by GBC (General Binding Corp, part of Acco) and was replaced by the CombBind C150 - just FYI. The lower-end machines such as this seem to run in the range of $200 USD.
I have never heard of sharpening these "blades", as they are actually punches, and there are likely some 20 small, individual "blades" that are part of the system. You might check with a local dealer or office supply partner, to see if they know of anyone who could or would perform the service and what they might charge for it. I believe that if you could find someone to do it, it would cost more than it would to simply replace the machine. There does not appear to be a way to replace the punch mechanism (die / strip usually) in these models.
An example of a machine with interchangeable dies is located at: http://www.factory-express.com/Binding_Machines/WireBindingMachines/GBC-TL2900/GBC-wirebind-TL2900.html
Obviously, this is a much higher-level (expensive) machine than the one you have here. But this is an example of the interchange concept, and associated costs.
So, this is a rather long way of saying, and trying to explain why I recommend that, you check with a local dealer perhaps, but plan to replace the machine. If it lasted you this long, the same level of machine should last just as well, and $40 US a year isn't too bad!
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