What is the value of a 1866 Winchester octagon barrel third model?

There are 3 distinct values for your rifle,if it is in below average condition then between 3,000-8,000 dollars.If it is in average condition then between 8,000-20,000 dollars.If it is in above average condition then between 20,000-35,000 dollars.It would be best if you had your rifle examined and evaluated by a member of the Winchester collectors assoc.