There is a way to calculate how much a legendary Item should cost. If we find out how many lootboxes you have to open to get at least one item with a specific chance, we basically know how much money we could pay to get a legendary Item. Since they are the most “valuable” items, we use them for now.
I have tried it out on this thread but we need to tweak a few things:
First, I used the average chance that at least one of the 4 Items are legendary but someone did calculate the chance of one item being a legendary item (and other rarities) which is 2.55%.
Second, we need to define a probability to get at least one legendary Item. The higher our desired chance is, the more Items we need to get. I think 97% seems to be fair for now.
Solving the “triple at least” problem, we find out that we need to get at least 136 Items or 34 Lootboxes until we earn at least one legendary item with a chance of 97%. Holy Moly That’s basically 34€ for one legendary item!
If we use the probability of getting an epic item, we’d need to open at least 10 Lootboxes (rounded up), which is odd because legendary items are 4 times more expensive in-game than epic items, while the chance of getting an epic item is 3 times higher than getting a legendary item.
What if we choose the comfortable middleman and say that a legendary item is worth 20€? This would mean that 50 in-game-credits cost 1€, which is the same amount of credits you’d get for leveling up. (I’d even assume that you’ll get less)
Disregarding other factors like offer and demand, etc. this would be the price of a legendary item if blizzard wants to earn as much money with the new shop system as with the lootbox system.