Unusually priced items in user shops?

I don't know if anyone else has noticed this... or if this has always been a thing and I was just slow to notice...

But when I'm food shopping for my Neopets I tend to like to look up one food item, then scroll through a particular shop buying all their reasonably priced food.

Lately though, I've been noticing some shops will have one or two reasonably priced items, and then fill the rest of their shop with normally cheap items up for hundreds of thousands of NP. For example, you might see something like a Rocket Fizzy Drink which normally goes for pennies selling for something random like 312,755 NP. And it's definitely several people doing this.

Any idea why? I'm stumped about it.