The empty boxes I've seen sell for £10 on eBay previous years. I'm lazy and can't be arsed to pack it up and go to post office etc.
Checking empty boxes on eBay though is a good tip for xmas packaging too. I bought an iMac in summer and bloke said to keep the box because they sell well and tend to go up in value when a particular model isn't supported. My particular box was selling at £50/£70 but things like empty Beats headphones, old iPhone or high end phone boxes etc. If you can hang on til next xmas you'll prob make a bit extra when people buy pre owned for gifts but need a box.
I thought today's was a hand cream at first. Love the cute little bottle. I'll be keeping the cute empty bottles to decant larger products in for travel. Much prettier than the generic £1 ones I usually use.