Price is a linear function (straight line) of the proportion of hourse for sale (positive slope), and also a linear function of the proportion of buyers (negative slope). 

Coefficients for the Supply Elasticity of Price and the Demand Elasticity of Price can be adjusted by the user using sliders.

Sales in each month are simply the lesser of the number of houses for sale and the number of buyers.

The number of houses for sale is a linear function of Price (positive slope) in a linear function of Price (positive slope) in the Flow "ToMarket" Coefficient for Price Elasticity of Supply can be adjusted using a slider.