An Autographed Copy

I have an autographed copy of Facing Mt. Kenya by Jomo Kenyatta. I wonder what it is worth. My husband actually won it years ago, shortly after Kenya gained independence in 1963. We were attending a function at University College Nairobi and late in the evening as the crowd was thinning, my then boy friend Ian was the lucky winner of this prize. This was in September 1966 when Kenyatta was the much revered Head of State.