Shaun Bythell's answer was to burn 3,000 of them.
He's the owner of The Bookshop in Wigtown,
which I've never heard of but apparently is Scotland’s National Book Town
& he chose to burn his excess stock on Beltane in Martyr's Field,
where 320 years ago Protestant martyrs died at the stake.
Of course his 24 fellow booksellers aren't too happy about the prospect of Wigtown
being known as "the place where they burn books" - Ironically one of the bookshops
is called 451F, a reference to the temperature at which paper catches fire.
(so named after the book by Ray Bradbury in which books are banned
and Firemen burn any that are discovered)
see here for the full story
I'm sure he could have found some people to take the books off his hands - I know a Bookcrosser or 3 who would have been happy to help him out.
Surely he could have found something to do with them other
than just dispose of them in this destructive & historically unsettling manner?