Amazing Crossway E-Book Sale
I recommend spending some time looking through the long list of Crossway authors, Ctrl+clicking on the ones you like (so as to open them in new tabs), and then going through the resultant books looking for some you need.
I almost bought Histories and Fallacies by one of my all-time favs, Carl Trueman, but for three bucks more I can have it in native Kindle format and they’ll automatically cull my highlights onto a web page. I find that to be worth three additional dollars. As it is, these Crossway books can be read on the Kindle but the highlighting feature is not quite as convenient. They do save your books to your account, however, so make sure you keep your username and password!