The Kindle version of Samin Nosrat's Salt Fat Acid Heat is currently $3.99 on both Amazon.com and Amazon.ca.
I'm not wild about cooking from ebooks but, in my opinion, the value of this book are the first 4 sections as named in the title. Great textbook for learning how to cook, especially if you take occasional breaks to watch her Netflix show of the same name. From Amazon's "Look Inside" feature, it looks like Wendy McNaughton's charming illustrations come through well.
The recipes that follow those sections certainly do work but this is also a book that you could just read through and get a lot from.
Edited to add:
The Kindle edition of Smitten Kitchen Everyday by Deb Perelman is $4.99 so maybe not a crazy bargain but still a good price for a solid book. I own the paper version and like it. This one is NOT currently bargain priced on Amazon.ca.