That depends on the knife and company in question. Hearsay is that some companies have very generous warranties and/or very reasonable repair services. I remember a thread a couple years ago about people buying up old junkers on ebay for a pittance, and then having them refurbished to practically new condition by the factory for very low cost.
Personal example- my brother has a Camillus Cuda Max folder he carried every day. Once while stipping some wire, the thing ended up getting dropped/flung onto the concrete floor and lost nearly an inch off its tip. I sent it back to the factory for him for repair. They charged him $15 to install a brand new blade. I think at the time that folder was going for around a hundred bucks or bit less new.
So, check out the company first. If they don't do repair work and you have to find an individual who specializes in it, then I agree with the others here and doubt it would be worthwhile from a cost standpoint in many cases.
