Baker Exegetical Commentary on the New Testament (8 Vols.)
Baker New Testament Commentary (12 Vols.)
Charles Simeon’s Horae Homileticae Commentary (21 Vols.)
New American Commentary (37 Vols.)
Baker Encyclopedia of the Bible (4 Vols.)
Encyclopedia of Christianity (Vols. 1–4)
Hermeneutics Collection (12 Vols.)
A. W. Pink Collection (40 Vols.)
Berkouwer’s Studies in Dogmatics (14 Vols.)
Continuity and Discontinuity
The Dictionary of Historical Theology
Dogmatic Theology, Shedd
Works of John Bunyan (61 Vols.)
Early Church Fathers (37 Vols.)
Analytical Key to the Old Testament (4 Vols.)
Beginning Biblical Hebrew (Futato)
Grammar of the Greek New Testament in the Light of Historical Research
A Grammatical Analysis of the Greek New Testament
Hebrew Grammar, by Friedrich Heinrich Wilhelm Gesenius
Exegetical Dictionary of the New Testament (3 Vols.)
A Greek–English Lexicon of the New Testament and Other Early Christian Literature, 3rd ed. (BDAG)
A Greek–English Lexicon of the Septuagint
Hebrew and Aramaic Lexicon of the Old Testament
Hebrew and Chaldee Lexicon to the Old Testament Scriptures, by Friedrich Heinrich Wilhelm Gesenius
Liddell and Scott Greek–English Lexicon
Depending on the interests of the person and money, I would commend the aforementioned books as valuable.