I have a Beeman HW30, 20 caliber that I purchased new in 1993. I am considering selling it and buying a more powerful springer air rifle, but I am having difficulty finding the value of this rifle. It appears to be different than a model HW30S which has an adjustable trigger and other different features. The original iron sights have been removed and a Beeman scope added. Can someone give me a fair selling price to set on this rifle?