Q:

How can I get total home values on Zillow? 

I am interested in getting aggregate dollar values for listings/sales on Zillow (for the whole country summed together, for example).  Unfortunately, Zillow's data page seems to only show the "ZHVI", an index value, not a total dollar value.  Is there any way to get the total dollar value? 

A:

To answer your question of whether you can get a number for 'total home value,' the answer is no–at least not easily. 
Zillow (somewhat) recently made available a data set similar to what you are searching for.  I suspect, however, that they do not want the public to have access to aggregated value because it would showcase the volatility of Zillow home value estimates, i.e. their algorithm-based estimate fluctuates much more than the estimates coming out of research institutions, etc. 
Sorry for the dissatisfying answer!