At work, we had a 12 volt power supply that powers a 20 year old car stereo. for speakers we use some that were out by the curb on trash day.
People would comment about how great our sound system sounded.
About a year ago, we wanted to upgrade a little. We have all of our music stored on the computer. In order to play the music through our sound system, we had to get a more modern car stereo that had a jack to plug in the cable coming from the computer. We now enjoy music with no comercials