By my calculations, for an American buyer, the 'in the door' cost for that gun would be about $2900.
Here is
a similar gun for sale sans case at gunsinternational, from Vintage Doubles in Washington, listed at $3400. There would be the additional $75 shipping and $50 FFL, so about $3500.
That brady case looks like it is in great shape. I don't think Brady is in business for guns any more, but
here is a used canvas covered Brady case for sale for $400 (plus $35 shipping) in the US. So, for US buyers, it seems that a similar gun and case would be close to $4000 or more. And there were 10 Churchill double guns for sale at Holt's today. There are 3 for sale total on gunsinternational and gunbroker today. (the one above at $3400, a sidelock for $32,200, and 1937 boxlock with price on request).
My takeaway is that the buyer of that gun got a great deal. I think it is also evidence that vintage guns are an outstanding deal compared to a new American gun like the
CSMC RBL which can be bought for $6600 plus tax, etc, Spanish guns like the
AyA 4/53 which can be had for closer to $8000, or the beautiful, Italian-made-British-branded
William Powell Sovereign sideplate that goes for $7464 presumably plus export/import costs.
The additional question of value buying from England seems clear to me as well-- there are more choices and better prices for high quality vintage and antique double guns abroad than we have here, and it is a great option even with the headache and expense of import.