This is just an estimation based on my experiences so please, dont try tell me this is right or wrong,its just my opinion, feel free to ignore it.
I based it on torch pack prices as for me, it’s the only constant, reliable way to collect the S class items.
So, theres a few torch pack deals, I tend to only buy at a 10 coin to 1 torch ratio. Although there is 130 to 15, but for the sake of simplicity, will settle on 10:1.
You need 166 torches to get 130 S class items, that’s going to cost you 1,660 coins. 1,660 divided by 130 is 12.76, we will call it 13. So in theory, 1 S class item is worth 13 coins… but we need 10,000, so we add another 4 zeros to our 13… 130,000 coins for your S class.
I’m not to clued up coin packs as I never buy any but if someone wants to finish the maths, please go ahead.