Measuring the economic impacts of GM crops in developing agriculture poses particular challenges. In order to ensure that information generated is relevant and usable, continued improvement in methods is needed as diffusion of these crops steadily expands. In the first decade of published studies, given the characteristics of early adoption, researchers were not often able to effectively control for various types of potential bias created by sampling, measurement, or estimation methods. Several published studies present exemplary approaches. The objective of pilot studies assembled here, all based on farmer surveys, was to attempt to apply recommended approaches within a constrained budget of $20,000-40,000 in countries and crops that had received little research attention. Case studies present findings, illustrate difficulties, and suggest means of overcoming them. Overall, we call for establishing research consortia to monitor the impacts of GM crops based on comprehensive national sampling frames in which ad hoc surveys can be embedded.