Sounds like a rifle 'anorak Adrian' might like to add to his collection.... a.k.a. draftsmann here on the BBS.
Might be worth giving him a PM as I think he's travelling this week, but he is in the UK.
The price you are after is (mostly likely) going to come from a collector, since buying this piece of history would seem like an investment opportunity, though Adrian does actually use the rifles in his collection IIRC.
HTH.