How is a block price decided when there are many products to be sold? For example the buffet in various restaurants or combos in McDonalds or KFC (like the bucket buddy). Can somebody point me to research papers or any link or book I can read to get into the logistics and mathematics behind pricing such combos?
I am not exactly sure what you mean by "block price" and I don't know the bucket buddy. However, I feel like you are talking about what microeconomists term bundling, the practice of selling two (or more) different goods together in one package.
Interestingly, bundling can be profitable even without any production-cost related efficiency arguments. It can serve as a tool to sort consumer types and thus can be used to price-discriminate.
The classical paper on bundling by a monopolist is McAfee, McMillan and Whinston (1989). For an introductory treatment of the topic read, e.g., Belleflamme and Peitz, Chapter 11 - or the corresponding chapter of basically any other textbook on industrial organization or microeconomics.