Many NIV Application Commentaries (NIVAC) on Amazon Kindle for $4.99 each

The NIVAC (NIV International Commentary) series for the kindle books is on sale for $4.99 for many of them until possibly May 20th.

The series is mainly for preachers and bible studies as it's split into 1) original meaning 2) bridging culture 3) contemporary application and it's so far quite good.

For which volumes are recommended you could start with the Denver Seminary OT and NT bibliographies which us an * for their recommended commentaries, or the webpage bestcommentaries.com. There are some excellent lists of commentaries there.

e.g.
Tremper Longman's 5 Star Commentary List
John Glynn's Ultimate Expositional Commentaries (OT)
John Glynn's Ultimate Expositional Commentaries (NT) 

The volumes that are well recommended are:

OT
Genesis - Walton
Deuteronomy - Block
Isaiah
Ezekiel
Daniel - Longman

NT
Matthew
Mark
Luke
John
Acts

1 Corinthians
Ephesians
Colossians ($8.60)
Philippians
1-2 Thessalonians

1 Peter
Letters of John
Revelation