Amazon is currently running a "buy three from this list, pay for just two" sale, which has a good number of Tolkien items in it:

https://www.amazon.com/promotion/psp/A ... collsguid-20&linkCode=osi

I do not know how long this promotion will be running, but there are some great prices at the moment (even before the free book offer)

Amazon.com (affiliate)
Letters From Father Christmas
Tolkien, J.R.R.
0618512659
(Paperback)
$13.79
Availability: Now

Amazon.com (affiliate)
The Silmarillion [Illustrated Edition]: Illustrated by J.R.R. Tolkien
Tolkien, J. R. R.
0063280779
(Hardcover)
$39.00
Availability: Now

Amazon.com (affiliate)
J.R.R. Tolkien 4-Book Boxed Set: The Hobbit and The Lord of the Rings
Tolkien, J.R.R.
0345538374
(Mass Market Paperback)
$18.54
Availability: Now

Amazon.com (affiliate)
Pictures by J.R.R. Tolkien
Tolkien, J. R. R.
0358653045
(Hardcover)
$17.79
Availability: Now

Amazon.com (affiliate)
Tolkien Fantasy Tales Box Set (The Tolkien Reader/The Silmarillion/Unfinished Tales/Sir Gawain and the Green Knight)
J.R.R. Tolkien
0345466462
(Mass Market Paperback)
$30.46
Availability: Now

Amazon.com (affiliate)
The Making of Middle-earth: The Worlds of Tolkien and The Lord of the Rings
Snyder, Christopher A.
1454944757
(Hardcover)
$25.49
Availability: Now

Amazon.com (affiliate)
The Complete Tolkien Companion
Tyler, J. E. A.
9781250023551
(Kindle Edition)
$12.99
Availability: Now

Amazon.com (affiliate)
The Art Of The Lord Of The Rings By J.r.r. Tolkien
Tolkien, J.R.R.
0544636341
(Hardcover)
$24.99
Availability: Now

Amazon.com (affiliate)
A Hobbit, a Wardrobe, and a Great War: How J.R.R. Tolkien and C.S. Lewis Rediscovered Faith, Friendship, and Heroism in the Cataclysm of 1914-1918
Loconte, Joseph
0718091450
(Paperback)
$13.59
Availability: Now

Amazon.com (affiliate)
J.r.r. Tolkien: A Biography
Carpenter, Humphrey
0618057021
(Kindle Edition)
$9.99
Availability: Now

Amazon.com (affiliate)
The Languages of Tolkien's Middle-Earth: A Complete Guide to All Fourteen of the Languages Tolkien Invented
Ruth S. Noel
0395291305
(Paperback)
$13.69
Availability: Now

Amazon.com (affiliate)
The Epic World of Tolkien: A Coloring Book
Editors of Thunder Bay Press
1645174581
(Paperback)
$12.99
Availability: Now

Amazon.com (affiliate)
John Ronald's Dragons: The Story of J. R. R. Tolkien
McAlister, Caroline
1626720924
(Hardcover)
$12.99
Availability: Now

Amazon.com (affiliate)
The Fellowship: The Literary Lives of the Inklings: J.R.R. Tolkien, C. S. Lewis, Owen Barfield, Charles Williams
Zaleski, Philip
0374536252
(Paperback)
$17.99
Availability: Now

Amazon.com (affiliate)
On the Shoulders of Hobbits: The Road to Virtue with Tolkien and Lewis
Markos, Louis
0802443192
(Paperback)
$11.99
Availability: Now

Amazon.com (affiliate)
A Secret Vice: Tolkien on Invented Languages
Tolkien, J. R. R.
000834809X
(Hardcover)
$20.49
Availability: Now

Amazon.com (affiliate)
J.r.r. Tolkien: Artist and Illustrator
0618083618
(Paperback)
$28.86
Availability: Now

Amazon.com (affiliate)
Tolkien and the Study of His Sources: Critical Essays
0786464828
(Paperback)
$19.99
Availability: Now

Amazon.com (affiliate)
Understanding The Lord Of The Rings: The Best of Tolkien Criticism
Isaacs, Neil D
0618422536
(Paperback)
$12.69
Availability: Now