What is a well used Dynavector DV20x low output worth?

I've had my DV20x for a few years but not massively used. That said, it must be towards the end of its life despite still looking good and a perfectly straight cantilever . Without a microscope how does one tell the condition and life of the stylus tip? Here in Townsville there are no specialist hifi dealers 😕

Does the cartridge have a minimum $ value for trade in? I guess that could be a starting point when I decide to sell

Thanks