In some cases the retail store just doesn't list the price and the store owner may just come up with a highly marked-up price when asked. 10x would be very rare though indeed.

What store doesn't list prices? Isn't that illegal in most places? In my country even the tiniest ancient village stores I've been to have prices listed on items (sometimes simple labels attached to the items, such as "10", but still there).

Some stores won't let you near the stuff they sell, you have to talk to somebody. Maybe that's what the GP is talking about.

Anyway, it's expected that you'll ask for the price and may go away after hearing it. So crazy mark-ups are risky business.

That only happens in shady mom and pop corner stores where laws are not enforced. Most countries force price listing and it's trivial to get caught.

You will see 10 X but it’s in places where it’s considered emergency go to the 24 hour gas station and look at the price of diapers or butt wipes compared to Walmart.

Yeah, but it's different if they list the price and it's huge, compared to no price listed at all.