The Schmidt & Bender 4X36 had a MSRP of around $850 USD last year.
When it comes to a package deal - gun + scope, I would not allowed more that $250-$400 (for me, it would be closer to $250) for it. This would be as long as the scope is not much older than 5-7 years.
Most sellers will separate their package as including a scope with the gun usually brings very little extra money.
The seller should seriously consider separating the package and selling the scope and the rifle separately but as a buyer, I would try to get it as a package keeping in mind the price range above.
If this is not the scope you want, you would have no problems selling it to recover your cost.
Duke1