Right now, Amazon US is offering a large number of Vonnegut's novels at $1.99 each.
Amazon (US)
It's not all of them - so if you don't want to click to find out. Here's the list:
Welcome to the Monkey House
God Bless You, Mr. Rosewater
Bluebeard
Galapagos
Deadeye Dick
Jailbird
Mother Night
Player Piano
Slapstick
Timequake
Bagombo Snuff Box
Fates Worse Than Death
Hocus Pocus
Palm Sunday
If you like Vonnegut - start clicking.