Well in my recent trawling of ebay I stumbled upon this fellow which I got for a very very reasonable £15.
He's a ltd edition Ultramarine Standard Bearer, released as part of the Skullz promotion in 1999/2000 (http://www.solegends.com/citle/citle2000/Skulz/skulzMarineStd.htm) , apparently to get enough Skullz to get him, you'd need to spend about £400, whether that's true or not I'm not sure. However, he's mine now and is going to be part of my Command Squad, which also contains the GD '98 Apothecary (http://www.solegends.com/citle/citle2000/GamesDay/gd1998apothecary.htm) and the OOP Captain I got last week too (http://www.solegends.com/citle/citle2000/armyboxes/ab40kMarineCaptain1999.htm). Plus some Tyrannic War Veterans. Also contemplating trying to get other Games Day Marine releases, but they're starting to get pretty pricey.
This is part of my project to build the whole named Ultramarine Command Structure, every company Captain and every named character. Will take a while, but will be worth it in the end.