Zondervan has a sale on 13 of it titles until February 15. Biblical studies titles include
A Theology of Mark's Gospel by David E. Garland ($7.99)
A Theology of John's Gospel and Letters by Andreas J. Köstenberger ($7.99)
A Theology of Luke and Acts by Darrell L. Bock ($7.99)
A Theology of James, Peter, and Jude by Peter H. Davids
Understanding Biblical Theology by Edward W. Klink III and Darian R. Lockett ($3.99)
You can access the sale here.