Morty knows he shouldn't be screwing around with multidimensional shit. It's dangerous, it's impractical, it's blah blah blah. But it's a potential key to unlimited energy, how does nobody see that? He's built a dimensional siphon (it kind of looks like a cardboard box with a funnel and a TI-84 taped to it, but it damn well works), keyed in the dimensional coordinates to a random plane, and by God he's going to use it.
He flips the switch and waits for the energy bar to fill up.
It does! It fills up very rapidly. Then it explodes, along with the box. There's rather more smoke than there should be, and once the smoke clears someone is standing there.
"Oh dear," Morty says faintly.
"Ah, that mess. Yes, yes. The card should be printed... here we go." A slot spits out a black card with a bit of heraldry on the front. "This has an allowance of $1000 per week; any extraordinary expenditure should be cleared with Mrs. Carson or myself. For your first week you have a starting fund of $10,000. Does all of that sound reasonable?"
"Unless inflation has been very different from projected trends at home, more than, yes, thank you."
"You return! In one piece, even! How was the harpy queen of the seven hundredth hell?""
"Absolutely. I want to view the marvels of the C-store. Last time I went in they had a pallet of seaweed. Not even, like, those bagged sheets of dried seaweed that people eat, just... bales of seaweed. Fucking bales. It is a house of wonder."
"...Why did they have seaweed? Why did they anticipate demand for seaweed?"
"I have no idea. But I saw some senior looking at them contemplatively, and by the time I came back it was all gone. So they weren't wrong."
"Huh. Okay. Let's see what wonders there are." Bella consults her map and puts them at the C-store.
"Huh, I've been meaning to pick up some amethyst." Ariel gets a large angular crystal and places it in a basket. After some consideration, she adds some rock crystal.
Bella grabs a couple of notebooks.
"I am," she says, "disconcerted, enough that I would like to look into how this is done."
"How what's done? The sales? It is pretty weird, yeah. We can ask at the counter or something, I guess. Shopping before or after?"
"...Before, may as well." Bella requires toiletries, bedding, a few changes of clothes, pens, and any interesting-looking reading material.
There is a great deal of interesting reading material, much of it on topics such as "the struggle of a closeted low-level Exemplar in Hollywood" or "the rise of Lord Paramount, an authorized fictionalization". Clothes are also available; however, Ariel scoffs at them. "Dude, you can teleport and you have ten thousand bucks. If you do not let me take you to Cecilia Rogers' shop I may never forgive you. Her stuff is superhydrophobic and bulletproof."
"Heaven forfend that you never forgive me or that I pass up the chance to own bulletproof clothes."
"Also it's all flawlessly tailored and it takes her half an hour to make you an entire wardrobe. Cecilia rocks. Trust me in but this."
"I do not have such strong opinions about my wardrobe that I will not take your recommendation here." Bella picks up some non-fictionalized history focusing on mutants.
To the counter; debit card exits pocket. "Hi. Do you happen to know how unusual stocking and sale decisions are made?" Bella woggles a notebook at the cashier.
The cashier is a student employee who appears to made of granite. His brow furrows at the question. "Listen, I, uh, I've only been working here a couple weeks. I know that it's weird, but I've got no idea how it actually works. There's some kind of computer in the back does the ordering. I'm pretty sure it's a devise, but that's all I could tell you. I guess I could get the manager for you if you're really curious?"
Ariel winces.
"As with our less mysterious devisor. So he can't tell us what the hell he was thinking, if we decided to call him up."