If you are interested in learning more about Luther's pastor, friend, and colleague, Johannes Bugenhagen, then these two volumes are a wonderful way to start.
Translated by Prof. Kurt Hendel and published by Fortress Press, they normally sell for $70.00. However, it seems as though a couple times a year they run a discount, and may be purchased for less than $20.00.
They are well worth keeping an eye on! http://fortresspress.com/product/johannes-bugenhagen-selected-writings-volume-i-and-volume-ii
Find more about this important reformer on our Johannes Bugenhagen page.