This study explores two important issues in experimental economics: calibration and auction institution. Consumer willingness-to-pay bids for corn chips made with non-genetically modified ingredients are elicited from a 1st price and 2nd price auction. Results suggest that responses to scale differential questions, in a survey, accurately predict consumer willingness-to-pay bids. The 2 nd price auction induces a greater percentage of marginal bidders to offer a positive bid than a 1st price auction. However, average bid levels in the 1st and 2nd price auctions were not statistically different from one other. In a small and unrepresentative sample, 70 percent of student participants were unwilling to pay to exchange a bag of genetically modified corn chips for a bag of non-genetically modified corn chips. However, 20 percent of respondents were willing to pay at least $0.25/oz for the exchange.