It could be said peace is priceles because the value of peace and the implications of living in a peaceful society or a peaceful world goes beyond money of the wealth witch could be associated with the power of nations or rich individuals.
Though, in these scary times we are going through, we must wonder what those governments and the radical organizations which are at war against each other are willing to pay or sacrifice for the sake of their own version of peace, to them peace does indeed have a price and they are already paying for it.
Israel is paying with their soldiers, Hamas had shown to be willing to pay by sacrificing the future of the people from Gaza. I won't even mention the case of Russia and Ukraine, because those are obvious.
The value of peace comes when we all stop for a moment and realize about the countless sacrifices which have been done in the past, so most of us can live a relatively normal existence.
One of the most vital point which I wanted is highlighted as peace is not completely priceless because sacrifice's must be pay to obtain peace even at the point of some sacrifice the peace is not completely hard by those that seek the peace , your point is valid as it connote that peace is priceless but demand sacrifice.
The point I sorta wanted to make is that when we people talk about sacrifice when comes to the context of geopolitics and international relationships, they are always talking about putting human lives at stake for the sake of national interests and in many occasions those interest have something to do with peace... Or at least the vision a society has about peace.
For example, during the Nazi Germany the National socialist party thought there would be no peace in Europe until all the Jewish population and the communists were wiped out, that is a vision of peace they had and they were willing to go to war for it, to sacrife their young generations for it.
Another example would be how Israel is willing to pay the price of the human lives of their soldiers in the pursue of what they believe is going to be peace for them and their country, regardless of whether they are actually doing (commiting atrocities against the innocent and other crimes) they are acting for their own interests.
That is the price I meant, and since we are talking about lives, it would be morally correct to say it is priceless. Thinking otherwise would be insensitive and typical of someone with a very dire and gloomy view of the world...