In On Writing by Stephen King, he mentions having sold the paperback rights to Carrie for 400K. Do publishers still sell paperback rights,Sure they do. For adult bestsellers.
and if they do, can they still get 400K or anything near that much?Sure they can. For adult bestsellers.
Speaking of sub rights, which ones are the most lucrative?The ones that are not for children's books.
Ok, I'm being just a teeny bit facetious. But it kinda depends on the book. Some books have good foreign potential, others will do better in paperback than in hardcover. Get yourself a good agent and consider the matter taken care of.