I'd always assumed the issue was with soliciting a value and then selling on here Tim, obviously because of the potential for arguments, etc...
My brother bought a similar rifle (same stock, handstop, foresight and buttplate but with a 2013 barrel and action and Hammerli rearsight) for £1000. That was an exceptionally good deal though, so I'd say somewhere in the region of £1000 doesn't sound unfair. It does depend on the level of usage of the barrel and the condition it's been kept in though.