This paper develops the structure and closure of an econometric regime-switching model within a partial equilibrium framework that has the ability to generate reliable estimates and projections of endogenous variables under market switching regimes. Models used in policy evaluation usually either ignore the possibility of regime switching using just a single method of price determination based on average effects, or incorporate highly stylised components that may not reflect the complexities of a particular market. This paper proposes an approach that the authors believe allows the incorporation of features of regime switching in a multisector commodity level model that capture salient features of the South African market and therefore are able to produce more reliable projections of the evolution of the sector under alternative shocks.