The Kindle version of Odette William's book Simple Cake has been at $2.99 for a while on amazon.com (sadly, not on amazon.ca)
The recipes are indeed simple although she gives a lot of variations for most of the recipes.
It's been the book of the month for the Food52 baking cookbook club and has been very well received. I made the Cinnamon Spice Cake (posted over here) and was very pleased with the result.