The "fair market value" is from the recorded sold price in the history (what a buyer will pay for the type of the property). There is no way to compare apple from orange. You will need to decide what will make you and your family happy and what your next home would be then you will have to make a choice between the size of the lot, the year built, the construction quality, and potential return value of your investment. I am sure there are other important components that are important to you. You will just have to figure out what they are and put down on a piece of paper so that you can see a clearer picture of a sound comparison particularly when you are comparing new and old properties.
Hope my lengthy response is helpful. Good luck to your search.
AmanVerde Real Estate
Tel: (512) 847-0180
Are you looking at new homes from a builder? You can ask the builder for their comps and see what other builders are selling for in the area.
Your agent should be able to get this info for you.
Let me know if you do not have an agent and would like some help.
Jeff Kessler,Broker, ABR,GRI