Many of Ed McBain's books are on sale for $1.99 today at Amazon US. Not sure how long this will last, and not as good as the $0.99 sale of legend a while back, but still pretty good. There are both 87th Precinct and Matthew Hope titles on sale.
McBain's 87th Precinct books are among the best (IMO) of the police procedural genre.
The link (sorry it's messy; I'm not a whiz at Amazon's seraches) is here: