Wherever you are, you can
A pay for an appaisal - good idea for estate where there are many family members.
B contact some REALTORS to give you some market valuation ideas.
C Call the municiple assessor to get sale information.
D Read the paper and search the web to see what is advertised privately for sale
Finally, I wish you the best and am a resource if you need anything. I do not service that area, but can suggest a top land REALTOR.