Second-life batteries are defined as those removed from electric vehicles (EVs) when their energy density and power density has degraded below the level required for motive applications but are still performant enough for less demanding stationary applications. They could one day be a plentiful, environmentally benign source of low-cost energy storage. Their price evolution is important to know for designers of and investors in such systems. A methodology is developed for predicting second-life battery price and sales quantities up to 2050. Although existing data is too scant to draw reliable quantitative conclusions, sensitivity analyses are run to investigate the effects of different EV uptake scenarios, new battery costs, refurbishment costs, recycling net credit, elasticity of supply, and size of demand. No previous work has incorporated all these driving factors in such a transparent way. The second-life price is found to be insensitive to most of these factors, while the quantity sold is sensitive to nearly all of them. Much work remains to be done in parameterizing the model more accurately. However, this work already elucidates a novel quantitative mode of thinking about what factors influence the long-term price and market size of second-life batteries.