If you are manufacturing and distributing copies of a song which you did not write, and you have not already reached an agreement with the song's publisher, you need to obtain a mechanical license. This is required under U.S. Copyright Law, regardless of whether or not you are selling the copies that you made.

Songfile® is a fast and easy way to license cover songs for physical, digital, ringtones and interactive streaming distribution.

http://www.harryfox.com/public/songfile.jsp