Here's a Lenscoat Hoodie X-Small soft neoprene lens cap - it fits 2.75" - 3.25" outside diameter lenses (that's 70-82mm). It is recommended by Ken Rockwell for the Sigma 8-16mm DX super wide-angle zoom, and it certainly makes the lens easier to handle in the field (it has a very highly curved front element). See http://www.kenrockwell.com/sigma/8-16mm.htm (but Ken's pricing is wrong for the UK!)
£21.00 via PayPal including RMSD to the UK.
I bought it from Cameta Camera in August 2011, but it's had virtually no use and has remained on the front of the Sigma most of the time. It looks a bit dusty in the photos below, but it's in absolutely mint condition.
This is for sale because I'm getting back trouble, and I'm lightening my wide-angle and normal zoom kit by a move to micro4/3 (but keeping my beloved D300 and tele Nikkors!). I'm also selling a Sigma 8-16mm, and my 16-85mm Nikkor (see the other adverts).
I'm happy to discuss sales to the EU by PM - in principle these would be at actual additional postage & insurance cost.