What is the value of a crosman arm 1-350 slide action bb gun?

Check you rifle again. I believe it's a V350 not an I350. The V350 is a push barrel rifle. It was made between 1961-69. In order to give you an estimate of value I need to know the current condition of the rifle. Is it still working? Is it in Poor, Fair, Good, Very Good or Excellent condition? Without more information it is not possible to give you an estimate.