I'm looking for an (ideally free) API that would have time series avg/median housing prices by zip code or city/state.
Quandl almost fits the bill, but it returns inconsistent results across different zip codes and the data is not as up to date as I'd like (it's mid November, and the last month is August).
I also looked at Zillow, but storing their data is against TOS, and at 1,000 calls daily--it would take forever to pull in the necessary data.
Any suggestions (even if they aren't free) would be much appreciated!