The link below shows the 14 lots currently for sale on Trulia in West Plains. Perhaps you can find a few properties comparable to your own that will help you to find this value.
Customer Service Representative
I have an Aunt who has 100 acres out there..in Peace Valley to be exact.
There are several Realtors out there that can run a CMA for you, (comparative market analysis) to give you an idea of what the property would go for by the acre.
Alot depends on what is on the property...improvements such as Barns, a home, etc.