I watched one K22 OD box on that auction site not too long ago, maybe a year ago. It was nicer than the $868 box. It was so mint that it looked as if it was just manufactured. Perfect. It sold in the high $400 range, like for around $475 or so to someone known in the community, but not a forum poster. I was tempted, but not at that price.
So if we assume your facts are correct, and there's no reason not to, the appreciation in value isn't quite double over a one year period. How's your 401k or IRA doing over this same period? I would think we have cheapskates who would even suggest the $475 price is/was out of line.
The most interesting thing about your post isn't the value increase on boxes, but the price increase in general. It always amuses me when we've got a poster who remembers the past so vividly, then goes to a gun show and see's prices he feels are way out of line. No question they would have convulsions over the box price, or even a similar box for half the $475 figure. But the reality is high quality items are in great demand by the collecting community. And they're willing to pay when a choice item comes up for sale.
Part of it is their perspective. They think of a gun box as something you leave on the floor of their damp basement, or pitch out in the first minutes of ownership. Some might even secretly lament having tossed out near equal condition boxes in their past. But many of us don't care about their opinions or motives. The reality is what counts, and its not what the grumps have to say. They're operating in the past.
I even sometimes smile and wonder what would have happened back in my new gun buying days had I found a gun in a shop I wanted. But when the clerk brought it out, I discovered scuffs or some other cosmetic defect in the box, and declined the purchase because the box wasn't pristine!

Most here would suggest I should be committed. Yet a fair number of new guns are delivered in a box that was just doing its job. That job is protecting the contents against evil.
And one last thought. Above GF posted a clandestinely obtained photo of 35 Registered Magnums in their boxes. The original owner wouldn't even buy a gun unless it was near perfect and in its box. Now those guns are up for sale, or will be shortly, for maybe an average of $10,000 each. So for somewhere in the neighborhood of $350,000 you could leap forward into the stratosphere of the big time collectors, maybe placing yourself at the very top. Sure, its a bunch of money. But its probably got the ability to increase in value at a much faster rate than your IRA. You remember your IRA, the one going up at .1% per year, and then you're going to be paying state and federal income taxes on it!
The rising tide is suggested to float all boats. This tide has done a much better job on collector or investment grade guns. Those of you that shoot and burn up your guns have even managed an undeserved increase in value.