West of Boynton Beach, a shopping plaza that opened just two years ago has sold for $37.5 million, more than double its assessed value. Tim Wilmath, the county’s chief appraiser, called the sale price a testament to how strong the South Florida market has become. Among the tenants at Cobblestone Commons, at Lyons Road and Hagen Ranch Road, are a Winn Dixie supermarket, PetSmart, Sports Clips, Club Pilates and a Burger Fi. The new company operates a number of industrial, retail and office complexes with almost all of them in Mexico.