I'm almost 100% certain they are out of print and no further editions are in the works. There were a couple being sold here in the proper For Sale forum within the last couple months for a very reasonable price of around $50.00 per ea. in new condition. That was a bit less than I paid for my copies
This guy who was selling in the proper For Sale forum had a few new copies of vol. II for only $50.00
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=544456#Post544456Used copies can usually found from online booksellers or on Ebay. Here's several available:
https://www.findbookprices.com/isbn/9781931220217/https://www.findbookprices.com/isbn/9780977415250/
