Over the years, I used to keep all my set boxes, collapsing them pretty carefully, and storing them away. But I decided a few years ago to stop, simply because I needed storage space. I was surprised to find, at the back of one of my storage units 3 large bins of boxes that I did not get rid of. There are hundreds of old set boxes in there. I didn't pull many out, but I did notice some of the larger ones, and they're classics:

6285 - Black Seas Barracuda
8880 - Supercar
4558 - Metroliner
6493 - Flying Time Vessel
Like I said, there are hundreds of them in there, large and small. Perfect for decorating your wall (which is what I did for years, before I started collapsing them!), making very cool posters, or even for your Bricklink store, if you have some older sets as pieces only with no box. I don't care what you do with them.
I may decide to keep a few of my ultra-favourites (like the afore-mentioned 6285 perhaps ...), but 99% of them must go. I'd hate to just toss them in my recycling bin ...

They're FREE to anyone who comes out to Abbotsford to get them (or arranges a suitable meetup with me.) Contact me by pm or email (buttons below).