Driver side seat belt 92 Cavalier

Hi, I have a 92 Cavalier wagon (Still runs GREAT). The plastic around the driver side seat belt has cracked off. This is the side with the clip and release botton. Can someone give me instuctions as to how to properly remove this and install a new one? Also, is the dealer the only place to get a replacement for this or can someone recommend another source. Thanks!!!

Hey, Just had an after thought. Does anyone know about how much I can expect to pay for this? I would really like to get it done before I end up getting ejected in an accident. It works okay as long as my body does not shift to the right :)
Thanks, Michael