A totally un-sponsored advertisement:
For the next few days, Olive Tree is offering a complete NT commentary series for US$40 (normally US$100) for iOS/Android.
Disclaimer: I don’t own it myself, but I do know the reputations of the scholars who have contributed to each volume, and I’ve flipped through some of the sample pages on Amazon for the hardcopy equivalents (e.g. Reading Matthew, David Garland).
It looks ideal for someone who wants more depth than a single-volume whole-bible commentary, but doesn’t want to pay $50-100 per bible book for the big scholarly tomes. The offer is until Dec 8.