Real boxes with packing material sell for $50-100 in decent used condition because they can elevate the sale price of the unit a few times that cost...or the unit owner is seriously cod with more funds than many AKers admit to spending on things like this.
Of course, if you have a nice older piece and the manufacturer still supports it, ask them what a box might cost and that $50-100 goes up but quick. Great to have original double boxes and packing for shipping a unit, too. This one is priced a bit high but it would sell if there was a best offer option.