Psalm 119:162 (NKJV)
The value of something can be determined by what someone is willing to pay for it or what that thing means to a person, what it is worth to them. There are some things that people have paid millions of dollars for, such as art work or other collectables, that have no real function in life but to those people they have value. There are other things, like a family heirloom, or a personal memento of some kind that have value to the people who own them. Even something simple like water can be valuable depending on the situation; value depends on how significant someone sees something as being.
In Psalms 119 David said he rejoiced at God's Word the way someone would if they had found a great treasure. It is interesting to notice that of all the Psalms that David wrote, the Psalm he wrote about God's Word, Psalm 119, is the longest. David understood the value of God's Word and because of that he rejoiced about it. But this is certainly not the attitude of many people, including Christians, today. Most people do not really see the Bible as valuable as a great treasure but that is what it was for David because David was a man who knew the Word and what the Word could do.
In Psalm 119 David talked about the Word being his counselor (v. 24), he was comforted by remembering the Word (v. 52), his hope was in the Word (v. 81), he did not perish in his affliction because the Word had been his delight (v. 92), the Word was a lamp for his feet and a light to his path (v. 105), those who love the Word have great peace and nothing makes them stumble (v. 165), and there are many other things he said besides these. What value do we place on God's Word, do we realize what God's Word can do for us? David rejoiced about the Word like it was a great treasure, do we?