A Drop of the Hard Stuff is the seventeenth in the Matthew Scudder series by Lawrence Block. It has dropped to $1.99 at Kindle and Kobo US. Block is probably better known for his Bernie Rhodenbarr/Burglars series, but I’ve read and liked many titles in the Scudder series as well.
A Drop of the Hard Stuff is $1.99 in the US again today. The links in the OP are still good.