You must file your copyright infringement claims in federal district court. Check this blog entry for more information. Unfortunately, the costs to file suit are increasing.
Specifically, the Judicial Conference initiated a new general administrative fee for civil cases filed in the district courts. The new $50 general administrative fee is in addition to the current $350 filing fee for civil cases and becomes effective May 1, 2013. So it’s going to cost $400 to initiate your copyright infringement case. Hopefully, you’ll be eligible for statutory damages and be able to recover your costs from the infringer.