Ayn Rand's Atlas Shrugged is easily the most famous libertarian novel of all time, and if you take anti-welfare state/laissez-faire regulation to be conservative viewpoints, you could also call it the most successful "conservative" novel of all time. This despite the fact that it is over 1,000 pages long, is full of l-o-o-o-o-ng philosophical passages, and isn't a staple of school curriculums.
I'm thinking of this because I just turned the last page of The Girl with the Dragon Tattoo, which reads like it was written by Tori Amos in the throes of an Adderall binge (though it certainly isn't a bad read). It has passages that are fairly unapologetic didacticism; all from a left-wing point of view. I'm a pretty avid fiction reader, and I cannot think of many right-wing/libertarian equivalents. Rarely do you encounter any contemporary fiction (or much past fiction, for that matter), particularly anything from a major publisher, that offers any alternative to the Progressive Consensus innate to nearly all editors, book reviewers, and literary professors (though they fancy this consensus to be obscure and rebellious). Maybe Tom Wolfe's Bonfire of the Vanities; not a manifesto by any stretch, but it does at least lampoon some progressive hobby-horses. Maybe some of Robert Heinlein's novels*?
So if you're shopping for a gift for a nephew or granddaughter, and you're a conservative or libertarian leaning person, what exactly do you have to choose from? You have to stretch your brain to make even a short list, and if you're not a major fiction consumer, you could easily be unaware of the existence of writers like Heinlein.
Probably the only libertarian/conservative novel that is consistently on people's tongues is Atlas Shrugged (or Rand's The Fountainhead). Maybe that is part of the explanation for its truly astounding success; it has no competitors.
*Orwell doesn't count; everyone thinks Animal Farm and 1984 are about the people they disagree with.