From The Gospel of Matthew by Curtis Mitch and Edward Sri, commenting on Matthew 13:45-46:
The pearl of great price parable offers a second illustration of urgency in responding to the kingdom. Though very small, pearls were considered more valuable than gold. As in the previous parable, the kingdom radically reorients one’s life. The one who discovers the kingdom joyfully gives up things he treasured in the past in order to obtain it, like a merchant who finds a priceless pearl and wisely sells all that he has and buys it. The merchant reflects Jesus’ first disciples, who left everything to follow Jesus (4:20, 22), and he beckons us also to prioritize the kingdom above everything else.