I began my business career by buying an existing Christian Bookstore (Waber Christian Supplies of Alma) in 1972. The Wabers had been in business since 1948. In 1981 I expanded by purchasing the remaining assets of a small Christian Bookstore in Mt Pleasant that was going out of business. Cook Christian Supplies of Mt Pleasant was located in the Campus Mall until 1988 when I moved it to 611 N Mission. On Friday, January 23, 2004, I sold the bookstore (Cook Christian Supplies) to longtime bookkeeper April Litwiller and her partner Deb Morey. That partnership was rather short-lived, though the Litwillers continued on with Cook Christian Supplies at the same location until 2010.

Cook's Music -Cook's Music began as a department of Cook Christian Supplies, and grew to what was at one point a chain of three stores in Midland, Alma, and Mt Pleasant. Cook's Music was sold in 1995 to Mike Otterbine. Mike sold the business in 2002 to Jim Gowen who moved the business from it's longtime location in 2005 and went out of business about 2 years later.. When Mike Otterbine sold Cook's Music, it displaced manager Brian Hansen. With Rob Cook's help, Brian then started his own music store, B's Music, in Alma. When Jim Gowen moved Cook's Music out of the longtime location at 613 N Mission, Mt Pleasant, Brian moved B's Music to that location.

Rebeats began as a department of Cook's Music. Rebeats is a business specializing in vintage and custom drum related items and activities. This includes production of the country's oldest and largest vintage & custom drum show held annually in Chicago, the publication of books related to drum history, video production, and the sale of books, shirts, calf heads,videos, etc. In addition to writing, publishing and distributing literature related to drum history under the Rebeats masthead, Rob does appraisal and consulting work. Rob also now uses the dba of Rebeats for his audio and video business activities.