I went to one of my local Rolex dealers
www.909.co.jp - not sure if they're an AD or not, but they exclusively stock Rolex. Anyway, they had a bunch of second hand boxes for sale. I went for some of the cheaper ones, also got a third smaller one (not pictured, but same as the small one but a bit more worn out). Total cost = 3,500 yen ($43 USD).
They had a range of other cool stuff for sale, so I might go back later and raid them again (had my daughter with me who started whinging).
I'm really pleased - I was going to buy a rep box, but no need now since I got myself a gen one
Better photos to follow when I get my DSLR back.
Some macros
Posting a few too many photos of boxes I suppose, but they're the only gen Rolex things I own.