Buy the truth, and sell it not; also wisdom, and instruction, and understanding. Proverbs 23:23
There is a hidden meaning behind buying the truth.
Of course we cannot really buy the truth with money. We can purchase it with non-monetary things.
What might those things be?
The cost of truth comes at a heavy price. All those who have preached the truth and those who believe the truth and follow the truth have given part of their selves to obtain it and to defend it.
That their hearts might be comforted, being knit together in love,
and unto all riches of the full assurance of understanding,
to the acknowledgement of the mystery of God, and of the Father, and of Christ;
In whom are hid all the treasures of wisdom and knowledge. Colossians 2:2-3
The treasures of Jesus come with a price.
Again, the kingdom of heaven is like unto treasure hid in a field; the which when a man hath found,
he hideth, and for joy thereof goeth and selleth all that he hath, and buyeth that field.
Again, the kingdom of heaven is like unto a merchant man, seeking goodly pearls:
Who, when he had found one pearl of great price, went and sold all that he had, and bought it.
Matthew 13:44-46
If you do not find the things of God of Great Treasure, they will not be so to you.
You will miss the true meaning of your existence and you will be forever without God as your choice.