Free market is working but prices are going up because the City is not approving enough housing to keep up with the amount of people moving here.  The Free market doesn't ensure prices stay low, it ensures that the price matches the demand.  If you want affordable housing you need to build more of it.  If you want fewer people living in Denver you need to increase the cost until nobody wants to live here anymore housing from being built.  The free market is working, just maybe not how some people want it to.