Are there so many of them being bought and sold that there can be a "going rate"?
The blued version is discontinued. Compare it to the current stainless steel version and decide how much more or less you are willing to pay to not have stainless steel. If you are buying a used one "new in box," try to find out if the manufacturer's warranty has expired and if not, whether it is transferable, and then decide how much you are willing to pay for that.