The Cobb County library branch at Merchant's Walk will be sold to a South Carolina shopping center developer for $1.3 million. The county commission Tuesday night approved the sale of the library to Edens and Avant. The Columbia, S.C., company plans to redevelop the Merchant's Walk shopping plaza, at Johnson Ferry and Roswell roads. Merchant's Walk is the third-busiest branch in the system, library officials said. Patrons circulated out some 543,108 materials in 2008.