Fortunately, you can gain access to a pared-down version of the MLS (Multiple Listing Service) database upon which many real estate agents rely. Almost all large residential real estate companies have links on their websites to the local MLS. You can search the database by school district, neighborhood, price limit, etc.
You can also visit the consumer website for the National Association of Realtors at www.realtor.com and search its MLS database. Even if you cannot easily find flip properties on MLS, you can find properties that fit your purchase profile except for the price. Those are the homes you should track in order to stay in touch with market values.