hello im thinking of selling my heanel 550-1 target gun. Its as good as it gets brand new box all the paperwork box bits, sights gun is immaculate ad shoots spot on. thing is there is nothing on the web, the only one i can see went on egun for 650 dollors but that was rebuilt and no bits, this has everything, and in new condition. so what do you think i should sell for? im guessing about 600 pound ? it also has the adjustable cheek and butt. thanks