CEDAR RAPIDS — Chris and Emily Thuerauf have sold elk meat at the Downtown Cedar Rapids Farmers Market every summer of its 15-year history. Normally crowded with hundreds of people milling about downtown Cedar Rapids, shoppers on Saturday picked up preordered food and jams by car.The Thueraufs, who own Antler Ridge Elk Ranch in Ely, can normally empty a 15-cubic-foot freezer of elk meat at the Cedar Rapids market.