What I've called "elastic pricing", has a true economics name that I believe I once heard.
Here's the notion: I walked into a gas station to buy a fountain drink. I only brought a dollar with me, but when I went to purchase the drink, I found out it was actually \$1.89. The cashier accepted that as payment - making a real-time decision that he was able to capture my demand at only $1. I ended up trying this at a few other gas stations, sometimes bringing 90 cents, and it always works.
An alternative to this is that my University just started pricing football tickets at a variable rate based on the location of the seats. Invariably, they were trying to capture the additional value that the second market was instead capturing.
A second alternative is that a former company of mine negotiated every price. So we would usually price the product at $500/user/month. But, we would always assess the situation, and with negotiation offer discounts, or increase the pricing. Or, provide value added services for free or at an increased rate.
So how do I talk about this flexible pricing concept – where a business sets it's pricing based on some kind of average demand, but considers an additional spread based on an individual's demand?
Edit: In my first example, the bargaining was only noteworthy because it informed a new mental model of mine – that the pricing was flexible. I don't believe it's an inherent component in the term I'm seeking.
As yet another example, consumer package good brands are known to alter their products slightly for online marketplaces – so that value savvy customers can't compare products directly online with those in the store. E.g. Duracell might offer a 6pk of batteries on Amazon vs. a 4pk at a retail outline. Or, they might package the item differently so it has a different SKU.