40 year old umarex potato pistol pristine condition, i want to know its value

i want to know the value of umarex patato gun at least fourty years, if there is someone with experience and knowledge of vintage airguns it would be appreciated
IMG_0272.1627939110.JPG
IMG_0273.1627939143.JPG
IMG_0280.1627939170.JPG
IMG_0271.1627939204.JPG