ESP has been selling stuff on their website for a little while now.
What I am assuming is, the 5*** number is just the receipt/invoice number tally from online sales on ESP.
Hell, during that run of numbers from last Monday and today, some folks might have bought a box of ESP or a folder and not even got a weekly card. So invoice 5**5 is a weekly card, 5**6 is a box of 2017 Elite and 5**7 is another weekly card.
I doubt we'll know how many of each card was sold/produced until they start arriving in folks' mailboxes. Card 1 could be XX cards. Card 2 could be XX - 12 cards and Card 3 could be XX + 234 cards. If they only <100 sold in week 1, either there aren't a lot of collectors going for it or might pick and choose, or folks don't know about it yet. Or they forgot. But let's face, how many hard core NRL collectors are out there wanting to spring $20 per week or $500 for the season?