There seem to be a lot of reasonably priced dross boxes on ebay at the moment. Not sure about some of the higher-end auction sites, since I haven’t checked them in a while. Boxes are definitely much easier to come by than pipes, that’s for sure!
Unbelievably there has been those 2 pop up on ebay. I scour the net and in a year and a half I’ve only seen 4 for sale. 3 of the 4 were sold by the same seller (he always has nice opium items) on ebay and I’ve seen 1 at auction grouped with many other items.