We present a dynamic model of an agent's decision to purchase or sell a good under conditions of uncertainty, irreversibility, and learning over time. Her WTP contains both the intrinsic value of the good and a commitment cost associated with delaying the decision until more information is available. Consequently, the standard Hicksian equivalence between WTP/WTA and compensating and equivalent variation no longer holds. This finding has important practical implications as it implies that observed WTP values are not always appropriate for welfare analysis.