I just got this new made box off ebay and wanted to share. I messaged the seller before buying asking if it was actually sized to fit 50 cartridges. He said that it was. It arrived today and I must say it is very nice! It does indeed hold 50 cartridges perfectly. I'm not expert, but it looks authentic to me. He has other boxes too.
It's nice to find a quality product at a fair price.