About $145,214 US, according to a study done by Media Development Research Institute Inc. in 2010. The breakdown of costs can be found here.
At first this may seem like a lot of money, but remember that they get back some money from sponsors, other merchandise, and any advertisements that run during its showing and during reruns on TV. With that said, competition among anime studios and for up-and-coming animators is still very tough in Japan. So it is always very important to support the anime that you like.