Economizing means the allocation of scarce resources. Scarcity is one of the most basic human conditions. And if it is a resource that is truly important, like health care, that is all the more reason to economize it.
Profit and markets are the best mechanism we have found to allocate limited resources. If it's an important resource, that is only more reason to economize it.
Two goods having about the same price means that, by and large, people would exchange these goods for each other. It means they have roughly the same value.
Now, if you want to "put a price on art", just tell me what you would exchange for a given painting. If you would trade a bunch of soup cans - that's what it's worth. If someone is willing to spend a million on it - that's what it's worth.
The nominal value we print on currency is arbitrary. If you added a zero to all of our dollar bills, our economy, after some hiccups perhaps, would roughly settle for good A and good B having the same price after if they did before.
