is worth its weight in gold
Une voiture vaut son pesant d'or.
A car is worth its weight in gold.
— Quand passent les cigognes (1957)
Cette peinture vaut son pesant d'or.
This painting is worth its weight in gold.
La satisfaction vaut son pesant d'or.
Satisfaction is worth its weight in gold.
She's worth her weight in gold.