The world is a strange place. Last week I sold a cardboard box on eBay for £15 purely because it had the words Apple iPad written on it. Prompted by this marketing success I currently have another such piece of merchandise for sale that nobody is touching with a bargepole at the same price....because it also has the word 'mini' on it.
At first I though this was a bit odd, as for accessories everything to do with the iPad mini seems to cost more that a full size one (even though there's less physical material in them and, simplistically, should be cheaper, but that's another story). It seems that although the old 3rd generation iPad box was snapped up at £15, the most I can expect anyone to pay for my discarded mini box is about £5 if I'm lucky.
I think this is down to the fact that most iPad Mini's are relatively new, desirable and holding their price. So having a box to sell it in if you are trying to get rid of one isn't that important.
For a 3 year old full size iPad (3rd generation if you are interested) having a box might make the difference between making a sale or not, so they are suddenly worth something in their own right.
All this lead me to thinking.....I bought my original iPad back in 2012....if a new box is worth £5 and the old one is worth £15, this is a 300% profit margin in 3 years and so probably makes cardboard iPad boxes a better investment opportunity than bordeaux wine!