The Faustian bargain. Yes, you can put a monetary value to it. Here is the thought experiment.
1: Think of the evilest person that comes to mind -- Hitler, Stalin, Mao, more contemporary equivalents.
2: Imagine this person approaches you at a meeting. He hands you a suitcase with the words: "Here is a present for you. Money. You can use it for personal purchases -- properties, cars, yachts, ... You cannot use it for charity or for political purposes -- saving children from poverty, supporting democracy, equality, ..."
3: What is the lowest amount of money that you would accept -- any amount, $10, $1,600, $9 million, ...?
4: Hey presto! That is the price of your soul.
Does your soul have a price? Does the price vary over time? If the price is made public, does it change?