Portia, I thoroughly enjoyed reading that!

It sounds like something was amiss in the housing/durable goods pricing. You can always suggest that your DS buy up the businesses that produce the more scarce products (e.g. vehicles, homes) and price discriminate. (Has he learned the different types of price discrimination yet? If so, try to have him optimise based on 1st degree price discrimination.) That should reduce demand for the durable goods/houses so it better aligns with his inputs, because demand will, presumably, be pretty inelastic for those consumption categories. Gotta love running a monopoly!
What is to give light must endure burning.