I offer the following for sale before putting them on ebay!
These have come off a new bike so have been used no more than round the car park!
11 speed 6800 cassette 11-28 - £30
rear derailleur short cage RD 6800 -£30
Also a 106 link (care - quite short) ultegra chain gratis for anyone who wants it - again not used I have a new link pin if you require or of course you could use a quick link.
Finally - two brand new Selle Italia saddles
(both c 290g and 135 x 280mm) make an offer?
£5 each to charity? Try before you buy!