I recently sold and purchased preowned AudioQuest power cables on US Audiomart with no issue. There are quite a number of AudioQuest items listed on Audiogon for sale by individuals. When you go to HifiShark and search for AudioQuest cables on eBay a number of countries come up but not the UK? Interesting.

Ultra DAC, Antipodes K50, Spiral Groove SG 1.2, Lamm LP2, T+A T1210R, VTL TL 7.5iii, Lamm M1.2, Wilson Alexia 1