I was researching for really good litter boxes (sizes) and found this thread. Just for fun, I checked the links, even though I knew the 2nd one was discontinued. Bed, Bath and Beyond states the item is no longer for sale online, and the Dr. Foster's link takes you to Petco.
So you were very smart to buy all of those boxes when you did, Lola, because it looks like they're not available anymore. Though I didn't check Amazon - too lazy.