While much research on prefiguration has focused on creating counter-alternatives in the present, projecting counter-alternatives from the present into the future is often overlooked. Drawing from the case of a grassroots organisation that confronted the shortcomings of the Kenyan banking system in serving the poor, we develop a framework of prefigurative imaginaries. This framework captures how the proponents use imaginaries to prefigure an alternative community currency system through two purposive actions – enacting social change in the present and foreshadowing future undesirable outcomes. However, when attempting to expand the alternative currency system on a larger scale, these actions fell out of sync, resulting in cracks within the imaginaries and eventually leading to the abandonment of the system. Our study unveils how grassroots organisations prefigure social change in marginalised contexts. Importantly, it underscores the significant influence of imaginaries on experiences and practices, ultimately shaping the acceptance or rejection of grassroots initiatives by the communities they aim to serve.