Hardly any Gun Dealer can get MSRP on a new rifle, unless it's a limited special edition. Even then they don't hold their value in the short term. All gun dealers have a 'used' rack, and that's where that rifle would go if the dealer had it.
I would call a dealer and ask for ballpark prices on that model rifle. Usually they can give you an idea what the value is, even without seeing it. As long as you can say what shape it's in they will try and help you out with a price. The price they give you is NOT the price they would pay you for it, it would be fair market value, generally speaking.
That rifle may be worth $400 or more to a person who wants one bad enough. If it seems like it's worth $400 to you, by all means pay it. I looked up prices at internet gun auctions and used 270's don't command a lot of money unless they are pre 64 or pre WWII. Even if you lost money in the beginning, it wouldn't be long before used rifles values exceed that price. Figure by the time you retire, you will realize a nice profit.
The main concern is to pay the going price for it.