To you the rifle was worth $300, at most. But I am thinking, how many 340 Savage's have I seen? Then I think a little deeper. The 225 Winchester was a calibre that just didn't set the world on fire. Then think of a 340 Savage in 225 Winchester! The bells are ringing, RARE.
You never mentioned what condition it appeared to be in, but if in collector condition it could have been a valuable piece. I will guess it was never shot too much, and it wouldn't have been dragged through the bush on moose, or likely even deer, hunts, so could have been in great condition.
As has been said, the buyer sets the price, or at least will snap up a deal when he sees one. One reason why a seller, not sure of what his gun may bring, will put a higher tag on it, just in case it is valuable to some one.
I was at a gun show in Yuma, Arizona, when a fellow walked in with a Model 94 W in 25-35 calibre. He went to about the first table he came to, told the dealer that rifle had shot a deer every year, never missed, etc, etc. When he quit talking the dealer took the rifle, turned it over once in his hands, then asked the fellow what he wanted for it. The fellow said, five hundred dollars. He had five hundred dollars in his hand so fast it would make your head swim.
The man went, the dealer took out a silicon cloth, wiped down the rifle and said to me, "This one is going in my car". I asked him what was so special about it. He said first the calibre, second the condition, then he showed me two minor (in my fiew) variations the rifle had and said, "This is rare."
Result, happy seller getting more than he expected and very happy buyer.