I don't often come across Lovejoy books in bookstores, new OR used. It just breaks my heart when bookstores go out of business. Back when Borders was still around, my husband and I used to make regular visits to Ann Arbor, MI because there were so many fabulous bookstores there. Shortly before we moved to Chicago, we made another visit there, and were devastated to find some of our favorite stores had closed.
The killer happened just weeks before we moved, when we had too much going on to manage a final visit. That was when Aunt Agatha's closed. The last day they were open, everything left in the store was FREE. We already gave away 1500 books before we moved, and brought more than 70 cartons of books with us. But, believe me, I would have made room for more!
https://www.detroitnews.com/story/business/2018/08/24/aunt-agathas-mystery-bookshop-closing-ann-arbor/1073037002/Back to Lovejoy. Here is a list of the Lovejoy books:
https://en.wikipedia.org/wiki/Lovejoy_(novel_series)
The other one I picked up is MOONSPENDER. I don't remember reading either of these, but I have read a lot of the books in this series already. My mom had most - if not all - of them, and I read everything she had. I occasionally came across early editions in the library, too. (This year's library sale was cancelled because of coronavirus. I sure hope it's back next year!)