I was under the impression that, in the United States, copyrights cost nothing
(a work is copyright as soon as it's created) and they last the lifetime of the creator plus 70 years. Trademarks
cost money to renew and have to be done every ten years. You can pay to have your copyrights documented by the government (I believe the fee is $35 for a collection) but this isn't necessary; it mostly just makes legal disputes easier.
Correct me if I'm wrong, but this is how I learned it through personal research and talking about it in an entrepreneurship class at college. I suppose I don't know anything about what happens when a company holds the copyright rather than the individual creator.