Rrelease back in July 2013, the LEGO Lord of the Rings 10237 Tower of Orthanc has been retired and is now sold out. The European LEGO Shop at Home has the set listed as retired while LEGO Shop at Home North America has it listed as sold out for quite some time. Official retail price at LEGO Shop at Home is as follows: $199.99 US | $249.99 Canada | £169.99 UK. If you don’t have this set and would like one, you should head over to your local LEGO Brand store to see if they have any stock available as UCS sets tend to get pricey after they have been retired! Note that this is also the last LEGO Lord of the Rings set that LEGO Shop at Home still has it in a listing.
Thanks to forum member eagerbeaver for the tip.