It's been said that salvation is free but the Kingdom costs you everything. What is the Scriptural substantiation for that statement?

In all of this, keep in mind that Christ died and provided complete salvation. The universalists then claim that everyone is saved--even those who refuse to believe and put their trust in Jesus. That's not true. Christ also died to create the Church, give ministries, give offices, give gifts of the Spirit, give the fruit of the Spirit, and give the manifestation of the sons of God and the progressive experience that leads to the manifestation. We can't earn any of those things. In universalistic thinking, all who are born again will automatically have all these things fulfilled in their lives. The reality is that we must lay down our faith in our own righteousness to be born again. Being born again really does cost us our self-righteousness and independence from God. At each stage of growth, we need to lay down what we have to pick up what Jesus has for us. In this sense, the Kingdom will cost us everything--but the good news is that everything we have is worthless.

Matthew 13:44 Again, the Kingdom of Heaven is like to 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.

45 Again, the Kingdom of Heaven is like to a merchant man, seeking goodly pearls:

46 Who, when he had found one pearl of great price, went and sold all that he had, and bought it.