I read this one a few years ago, but I gave it four stars on Goodreads, so I thought I'd recommend it! The sale is two days- through May 8th.
My rating: 4 stars / I really liked it
Synopsis from goodreads.com
An unlikely attraction occurs between two passengers on a steamboat journey up the Missouri River to Montana...
She is a self-centered young woman from a privileged family who fears the outdoors and avoids anything rustic. He is a preacher living under a sense of duty and obligation to love the unlovable people in the world. She isn't letting anything deter her from solving a family mystery that surfaced after her mother's death. He is on a mission to reach the rejects of society in the remote wilderness regions of Montana. Miss Fannie Rousseau and Reverend Samuel Beck are opposites in every way... except in how they both keep wondering if their paths will ever cross again