For a single-volume Bible commentary, the apologists at Catholic Answers often recommend Bernard Orchard’s 1954 book, A Catholic Commentary on Holy Scripture, published by Nelson. However, the book is no longer in print. Maybe you can pick up a used copy somewhere.
A single-volume commentary that is widely available and might meet your needs is Bishop Frederick Justus Knecht, D.D.'s 1923 book, A Practical Commentary on Holy Scripture, published by TAN. It is based on the Douay-Rheims Bible. Here’s a link to a
description. If you are not in a hurry,
Amazon.com seems to have the cheapest price at $19.80.
For something more scholarly and more reflective of current modernist trends in Catholic Bible scholarship, you might consider The Catholic Study Bible: New American Bible by Donald Senior, et al., published by Oxford University Press (1990). It is widely available.
Amazon.com carries it and you can browse a few of its pages at their website.