This is like if a Yandere level 1 was dating a Yandere level 8 lol~
Let's see, each full box/storage has about 12 lip balm which is 18 boxes for the ones we could see (assuming 12 for the cut offs for simplicity). The current one is at 6 balm. And 1 lip balm is ¥208.So if we calculate ((12x18)+6)x208. Girl, spent about ¥46,176 so almost $300. This girl needs better hobby, I swear kids these days.
Your calculations seems mostly correct except I think you got forgot to add the fact that in (page 3) the 208 yen lip balm (Yuri theme/brand) has 2 lip balm per pack [A pack of 2 for 208 yen.] This means 208 yen for about 2 sticks or 104 yen per each lip balm.
So almost $150 dollars I think? Still a lot of money but even if it was spread out over months or if she had a part time job then not that much money...Probably has a well off parent that gives allowance though XD