Past home sale prices are now public knowledge. The information is available from the county in which the property is located. If you are working with a Realtor, his MLS may show previous sale information.
You can try zillow.com and put in the address. Also, search deeds for your county seat. If your county puts this information online, you will be able to find it there. If all else fails, you can physically go to your county office and search property records.
Deborah Madey - Broker
Peninsula Realty Group - New Jersey