Cardboard Recycling boxes free
I'm not sure about cost efficiency, at least in the short term. If you think about it, these boxes are pretty cheap, especially when you get them in the quantity that Amazon does.
Environmentally though, it would definitely make sense to reuse them. One thing I wish big online retailers would start implementing is a 'box-fee' (or 'box-rebate', depending on how you want to look at it). If you return the box your item comes in, you get a rebate for it.
Implementation wise, it should be relatively simple to set up. Each box gets a barcode assigned to it. When you're buying your product on, you're told how much of a rebate you could get if you returned the box. This would vary depending on whether you want a brand new box, or are willing to have your product mailed in a used box.
would also have to set up predetermined collection spots…either they could build something from the ground up, or they could pay /designated retailers a certain fee each month to start collecting boxes from customers (similar to those 'Authorized UPS Shipping Outlets' you see all over).
The total rebate a customer gets is computed by scanning in the barcodes of the boxes they brought in. Then, the boxes get sorted by quality and size, ready for pickup and reuse.
It's actually a really similar idea to cans/plastic bottles, only with a little more technology thrown in for tracking purposes. I imagine the short term cost-efficiency would also be similar to recycling.
(Alternatively, could also get his to pick up your boxes when it delivers your goods if that turns out to be more efficient.)
Some challenges I see to widespread implementation of this:
Some of these boxes aren't tiny so the collection center is going to need to have space to store them, and the amount of money they make from it is going to need to be large enough to make up for the inconvenience.
The box needs to be sturdy enough to protect the product its carrying - some products rely a lot on the packaging to protect it from damage while others really just use the box as a convenient way to group everything into one nice bundle. There's going to need to be some kind of automatic (i.e. algorithmic) categorization system that will designate which box gets used for which purpose. This might not be that big of an issue though since the customer still gets to pick what kind of box they want to use (brand new, used once, used twice, etc)