First and foremost, when buying investment property, you need to get to know the areas where you will be making offers. Your “farm area” is the area where you intend to concentrate your marketing efforts. You can get a lot of this information from the MLS (Multiple Listing Service) by doing a search of all the homes that have sold in that area during a specific time period.
Another good way to find out the values of homes in a particular area, is to get in your car every Sunday and hit all of the open houses in your farm area. When I first opened my home inspection company many years ago, that is exactly what I did. I took a coffee mug full of “goodies” (a pen and pad of paper with my company name and logo, some chocolate, mints, a tea bag to make a cup of tea, etc) and gave it to the agent. I introduced myself when I arrived and spent a short time chatting with the agents. In the early years this really helped me to build my business.