Has anyone else used Lulu? The resources in print there are astounding for stuff like this. There is a commentary available from St. Alphonsus Ligouri on the Psalms for $10 I might pick up too, which follows the order in the Psalter.
I splurged for this $14 edition for reviewal purposes and also as a hold-over for the forthcoming Baronius Edition. (With shipping it cost $22.) For someone on a budget its a great deal. In the "Thank You" email from Lulu, the editor has asked for error scanning from his buyers. So let's help him out by doing so!
This edition is also available as a free download, so at least take a look in your spare time.
Meanwhile, my Anglican Breviary is doing me great service. My thoughts on it are still on the way...