Well, if you think you can get in any last minute purchases:
Stephen Booth is a UK crime writer who's been published by Little & Brown. He offers one free-with-coupon novella, and 50% off a novel which he says was "a finalist for the Crime Writers' Association's Debut Dagger Award in 1998".
Randall Luce quotes a Publisher's Weekly review for his free-with-coupon historical mystery set in New Orleans.
Stephen D. Rogers says he has a Derringer Award and offers a free-with-coupon collection of solve-it-yourself mystery shorts.
D.L. Kung claims to have been a reporter in China for over 20 years. Very likely pure self-pub, but the 1st in their Hong Kong set series is free with coupon and looks interesting. 25% off the sequels.