Can We give any value to anything in truth? Isn't everything in this world equal in value? Can we say that the value of a human being is greater than the dust?
Your question reminded me of this Zen koan

Dead Cat Treasure
There once was someone who asked Ch'an master Ts'ao Shan, &quot;What is the most expensive thing in the world?&quot;
&quot;The head of a dead cat,&quot; was the answer.
&quot;Why?&quot;
&quot;Because nobody gives it a price.&quot;
Commentary: By using the image of a dead can, Ts'ao Shan tried the destor the common virtues of the ordinary mind. On the other hand, [etc.]

That might be memorable or striking -- but I didn't find it easy to understand when I first read it.
There appears to be some explanation of it here (but beware that people say that explaining a koan will spoil its effect on the reader). This explanation seems to criticise the master:

In his book Pointing at the Moon , Alexander Holstein offers an explanation to the  above mentioned answer of Zen master, as being his attempt to teach his disciple to “destroy the common values of ordinary mind”.
As it is evident in this teaching, the answer to “what is valuable?” - was answered here  based on “what is not valuable” in the ordinary view of people. Zen master of this koan does not know how to answer a question on what is valuable in Buddhism, and takes what is regarded as not-valuable (in the mind of common people) as a reference to say something.
Additionally, the master’s aim to “destroy the values of ordinary mind”  - is non-Buddhist in essence. Nichiren teaches, that the ordinary mind of ordinary people (of the Nine Worlds) contains within it the Buddha mind (Buddhahood) as well.

I think that's saying that to ask &quot;What is expensive?&quot; or &quot;What is valuable?&quot; is ordinary and unenlightened thinking -- i.e. what I might think of as, &quot;the wrong question to be asking&quot;.

There is incidentally a proverb or idiom in English (not Buddhist), &quot;The best things in life are free.&quot;
What Does The Best Things in Life Are Free Mean?

Someone might say, “The best things in life are free” to celebrate something that he enjoys that has no monetary value [...] for example, after spending a day on a hike through nature
Someone can also use this phrase as a warning, [to] indicates that a person is forgetting about the things that truly matter in life.
The phrase the best things in life are free expresses that happiness comes from places other than money and objects.

I think that may normally be non-Buddhist if it involves delighting in and attaching to experiences, but even so.

I'm not sure whether this is inline with Oyamist's answer, but here's another Zen story:

Inch Time Foot Gem
A lord asked Takuan, a Zen Teacher, to suggest how he might pass the time. He felt his days very long attending his office and sitting stiffly to receive the homage of others.
Takuan wrote eight Chinese characters and gave them to the man:
Not twice this day
Inch time foot gem.
This day will not come again.
Each minute is worth a priceless gem.


The suttas tend to talk about what's &quot;praiseworthy&quot; rather than about what's valuable -- virtues like harmlessness, generosity, ethics, good will, discernment, right speech, wisdom.
Perhaps we should also consider as &quot;valuable&quot; that which is &quot;instrumental&quot; -- for example, a hammer is valuable (a useful or essential instrument), when you want to hit a nail.
Similarly the noble eightfold path is valuable; the Three Jewels (Buddha, Dhamma, and Sangha); or see for example AN 11.1.