We are creating an analytical tool for real estate in USA and have a problem getting a ballpark estimate on data costs, as companies like CoreLogic who has this type of Data are not answering on how much this type of data would cost. Maybe someone knows a ballpark estimate on how much would it cost to get a bundled transactions data of residential real estate (sale date, sale price, pictures of sold properties) mainly we are interested in California, but the whole USA data would also be of interest. The same question would also apply for Canadian market, as governmental institutions who hold this data are extremely slow in giving their answers.
Separate, but related note:
"NYC Open Data" is growing every day & provides free data
For national data check out the parent organization Socrata.com.
Great resources for public data records, which are 100% free, contains everything from real estate transactions to the number of public bathrooms...
Best of luck tracking down the costs.