It'll say to buy an item at some low price between 1000 to 2000 sP and then suddenly...
You've purchased a Cream Mortiking Elixir for 124,580sP!
WHAT. This has happened to me twice already. I'm filing a ticket because I really don't have that kind of sP during lumi, don't pull from the Mystery Box today y'all.
The Mystery Box cost is nearly double the official price, and many of those elixirs are around 60k. The Apocalyptic Apothecary is one of those shops where you have to be careful when pulling out items.
No, I understand that! I've used the mystery box plenty of times before! The problem is the box tells you how much you'll pay before you pay, right? It's working for some items (saying you can buy an item for ~150-190k) but it isn't working for others - no elixir is 1,428 sP in price and that's clearly not a multiple of any of their prices.

I agreed to pay 1,428 sP, not 170k.
Again, the problem isn't that I'm being charged a multiple of the price. The problem is that it's showing one price and charging another.
Edit:
Normal function!
Will still charge you over 150k! (edit: or 120k after looking at my history, marginally better lol)
Have you tried hitting try again a few times until you get to a strangely low price? That's how I've been getting to these, they show up like... 1 out of every 6-ish refreshes on average?
Yes, I've only been buying the low priced items and it charges me correctly. Even made sure to keep an eye on my onhand sP. I guess I wouldn't use it if I were you for today =/ at least until someone gets back to you.
There are glitches that affect some and not others. Maybe this is a that sort of thing?