[Retric]

Seems reasonable until prices are updated based on who is looking at them or when someone has something to their cart.

[pfannkuchen]

It seems like if this were a real danger then it should have already happened on the internet.

I'm aware of broad geo-based price differences, but it seems like you could also tailor the price based on browsing history (via cookie networks, etc). Has this happened?

The increasing cookie restrictions over time could get in the way of this, but I haven't heard of it ever being a problem in the first place.