Startup Idea : Properties appreciation/depreciation map

It's a tool to aid sellers/real estates and buyers to assign or beacon and consult propertie prices based not only in the conditions and qualities of the propertie itself, but also on locale related factors that the tool should display in a quantified way. Factors like public improvements, existence of basic condidions (water/sewer systems), commercial centers, floods, crime index -- and the likelihood of increase or decrease in this factor --, paved roads, playgrounds. etc, etc... I don't know if it semms like crazy, but it would be a great help for buyers who usually have to accept imposed prices by sellers...