If you are thinking about buying the PBC (as you should!) now is the best time because your purchases combine with others to give the book the biggest possible boost on Amazon ranking, which in turn helps with search results and visibility to the larger community of music buyers. The book has moved from 1 million to 6,000 in a couple of days, but it would be best for it to rise to the 100s if possible. You can help that effort by buying now.
Catholic musicians gathered to blog about liturgy and life