I can recommend https://www.goodreads.com/book/show/12391759-12-million-dollar-stuffed-shark https://www.goodreads.com/book/show/12391759-12-million-doll... "$1

I can recommend https://www.goodreads.com/book/show/12391759-12-million-dollar-stuffed-shark https://www.goodreads.com/book/show/12391759-12-million-doll... "$12 Million Dollar Stuffed Shark: The Curious Economics of Contemporary Art and Auction Houses" around these topics too. For someone without any background in art it's very approachable. Gagosian is mentioned many times in the book.