This is a repeat but it looks like most J.R.R. Tolkien books are on sale at Amazon and Kobo.
This is
Tolkien Reading Day so it looks like Amazon and Kobo (possibly others) are having some big sales.
The Lord of the Rings (Complete) - $1.99 -
Amazon
The Hobbit - $1.99 -
Amazon 1 - Illustrated:
Amazon 2
The Silmarillion - $1.99 -
Amazon
History of Middle Earth Series - $1.99/ea -
Amazon
There are a few at $2.99 or higher but those are not the majority.
Note that there are multiple versions of some of these books. You might want to double check your library to make sure you don't get a repeat. For example, I have 2 links to The Hobbit above. I already have one of them but it was the second I checked. There are also both omnibus and individual volumes of the Lord of the Rings available. You can get each individual volume for $1.99 or the complete version (link above) for $1.99.