You guys are amazing. So much to choose from now!
We're only buying maybe like ten, maybe less, maybe more depending on the total price. So any repeat recs or seconds or thirds to any of these authors or books will help me out on deciding too! I think I'm going to do about half the ones that sound good that she probably has the least chance of having read before, and the other half ones that have most recs in this thread or best reviews elsewhere and just hope she hasn't read them, to give her a good mix of more obscure and more popular to choose from.
For my own reference, to have them in one place, here's what I'm going to look into:
Brad Meltzer (thrillers)
John Hart (mysteries)
Peter May's Enzo Macleod books (like Dan Brown)
Mark Billingham's Tom Thorne books
Val McDermid - The Mermaids Singing (first in series, police woman and criminal psychologist)
Robert Crais - The Monkey's Raincoat (first in Elvis Cole series, nominated and won mystery awards)
J. D. Robb's In Death series (sci-fi set 50 years in future)
P. D. James
Carol O'Connell
John Verdon - Shut Your Eyes Tight (excellent psych thriller)
*Dennis Lehane's Kenzie-Gennaro series starting with A Drink Before War and Darkness, Take My Hand
Tom Rob Smith - Child 44 (thriller, first of trilogy)
Tony Hillerman's Leaphorn & Chee Mysteries (Native American investigators)
**Dana Stabenow's Kate Shugak Mysteries by (Native American investigators) (FIRST ONE FREE - a cold day for murder, see links)
Dana Stabenow's Liam Campbell mysteries (FIRST ONE FREE - fire and ice, see links)
*Kathy Reichs (like Patricia Cornwall, Bones tv show based on it but very different)
Jefferson Bass' Body Farm series
jgaiser's recs:
Craig Johnson
James Elroy
Lawrence Block
Truman Capote (In Cold Blood)
Raymond Chandler
Lee Child
G.K. Chesterson (Father Brown??)
Reed Farrel Coleman
Michael Connelly
Sue Grafton
Dashiel Hammett
Georgette Heyer
Laurie R. King
John Le Carre
Ed McBain
free classics:
Josephine Tey's Alan Grant mysteries (possibly free)
Agatha Christie's first books, Mysterious Affair at Styles (free)
Sherlock Holmes (free)
Wilkie Collins - The Woman in White, Moonstone (free)
Dorothy L. Sayers (free at mobileread)
Edgar Wallace (free)
And thanks cassidym for the Literature Map rec. There's so many recs here and I can't get them all, so I may use that to see which of these recs might be close to some of her favourite authors.
Synamon, that's a great idea, I hadn't even thought of filling it up with free older ones (even when you first mentioned free in your first post, heh)! I'm guessing she'll probably stick mainly to the newer/newest ones that she's now used to if she uses the e-reader at all, but no matter, it's still a great idea since it's free and will fill the library out and she just may get the urge to revisit one or try one sometime. Now I'll be able to fill it up with all sorts of classics, maybe even some non-mystery ones she might like, so she can have not just some books but a good sized smaller library on it ready to go right from the start.
So definitely, if anyone else has any free classic mysteries to recommend that I might not think of, I'll take those recs too, thanks!
ETA - If I missed either commenting on or listing anyone's recommendation, it was only by accident so let me know, but I think I got them all.