Nested Regression with continuous dependent variable




Does anyone know what model to use for the following issue:

I would like to estimate transaction size (continuous dependent variable) using various predictors. But I would like to condition the regression on whether the buyer and seller are located in the same state (dummy variable with 1=same state, 0=not same state). If I understand it correctly, a nested-logit model requires both stages to have a categorical variable, therefore what model do I use for conditioning a continuous dependent variable on a binary variable?

(I am using SAS)

Any help would be appreciated!