X-link to the Non-Fiction thread for a Tolkien-adjacent annotated companion:
@ $1.99 in the US only,
The History of the Hobbit: Mr Baggins and Return to Bag-End by John D. Ratliff & the late J. R. R. Tolkien, which gives a history of the making-of, plus commentary and additional bonus materials including the complete unpublished draft version of the story and several previously unpublished maps drawn by Tolkien himself.
Also, @ $3.99 each in the US only from HarperCollins, some additional Tolkien shorts in the rather nifty-sounding illustrated versions also with extra bonus material (for comparison, $12 CAD each):
- The Adventures of Tom Bombadil, which is apparently poetry starring one of the Middle Earth characters with illustrations by Narnia artist Pauline Baynes, plus additional material and annotations by Tolkien scholars.
- Smith of Wootton Major, a standalone post-fairy tale fantasy short story also illustrated by Pauline Baynes, including as bonuses an early draft manuscript, an alternate ending, annotations, plus an essay on the nature of Faery.