A relational property
Value is never fully described by the object alone. A glass of water changes meaning in a kitchen, a hospital, and a desert. The object remains; the surrounding system changes its function.
This does not make value arbitrary. Systems have real constraints. A bridge either carries its load or it does not, regardless of the story told about it.
Beyond price
Markets compress many judgments into a price, but leave out functions that cannot be owned, measured, or exchanged cleanly: trust, belonging, ecological stability, practical knowledge, and time with another person.
The value questions
What function does this provide? For whom? Inside what system? Over what period? What must remain true for it to continue? What does it displace, consume, or place at risk?