has discounted a bunch of their books down to $3.99-$4.99
at the US Kindle site (haven't had a chance to check the other bookstores).
This is a bit unusual since I've hardly ever seen any discounts from them. There's more than 100 discounted books to wade through, many of them nonfiction. Here's an Amazon search link for those published by Penguin
and search links for those published by Penguin imprints Plume
, DUTTON CHILDREN'S
, Gotham Books
to browse through the bargain books.