As a follow up to the last post: amazon has also omnibus editions of various (crime)-series on sale. Like those two:
Carola Dunn's Lady Daisy Mysteries
A charming cozy mystery about an impoverished aristrocratic lady in 1920s England who keeps stumbling over dead bodies (seriously: if I was one of her friends I would simply not invite her to parties anymore..somebody always ends up dead). The first book was admittedly nice but not overwhelming but the series really picks up.
Colin Dexter's Inspector Morse
If you ever wondered about the books the TV-series is based on. I enjoy it a lot (though with reservations..the books were written in the 70s/early 80s and some comments the characters make, make this painfully obvious...or to put it plainly: sometimes they say things that are cringeworthy sexist from today's POV).
There are more omnibus-editions on sale (like Hamish Macbeth & Agatha Raisin) but those are the only two I already read and enjoyed.