If you write your book in pidgin,it means that you wrote the book for only a particular people because it will be hard for you book to sell beyond the shores of those who don't know how to read pidgin or those who don't understand pidgin. Think vast and use the common English language that is the most spoken language in the world. You don't know where you book will get to tomorrow.
Have you read books written in pidgin English?
I have never read any book in pidgin because it will not draw my attention
Will you buy a book written in pidgin English?
No, I wouldn't because I will not fancy it.