Is it biblical to sow seed (money) every time we seek something from God as some prophets and pastors claim?
First off we have a problem because there are no modern-day prophets. So we are dealing with people pretending to be something God doesn't approve of. See:
Second, you need to understand that God needs nothing from you. He created the entire universe.
"Hear, O My people, and I will speak, O Israel, and I will testify against you; I am God, your God! I will not rebuke you for your sacrifices Or your burnt offerings, which are continually before Me. I will not take a bull from your house, nor goats out of your folds. For every beast of the forest is Mine, and the cattle on a thousand hills. I know all the birds of the mountains, and the wild beasts of the field are Mine. If I were hungry, I would not tell you; for the world is Mine, and all its fullness. Will I eat the flesh of bulls, or drink the blood of goats? Offer to God thanksgiving, and pay your vows to the Most High. Call upon Me in the day of trouble; I will deliver you, and you shall glorify Me" (Psalms 50:7-15).
If God gave preference to the prayers of people who first gave to Him, then He would no longer be the impartial God (Romans 2:11). "For who has known the mind of the LORD? Or who has become His counselor? Or who has first given to Him and it shall be repaid to him?" (Romans 11:34-35). Notice that these false teachers are telling you the exact opposite of what Paul said. God owes no man anything; we owe Him everything.
I believe the passages these false teachers are misusing are those which talk about sowing and reaping the consequences of our behavior.
"Sow for yourselves righteousness; reap in mercy; break up your fallow ground, for it is time to seek the LORD, till He comes and rains righteousness on you. You have plowed wickedness; you have reaped iniquity. You have eaten the fruit of lies, because you trusted in your own way, in the multitude of your mighty men" (Hosea 10:12-13).
"The wicked man does deceptive work, But he who sows righteousness will have a sure reward" (Proverbs 11:18).
"For he who sows to his flesh will of the flesh reap corruption, but he who sows to the Spirit will of the Spirit reap everlasting life. And let us not grow weary while doing good, for in due season we shall reap if we do not lose heart. Therefore, as we have opportunity, let us do good to all, especially to those who are of the household of faith" (Galatians 6:8-10).
"Now the fruit of righteousness is sown in peace by those who make peace" (James 3:18).
Notice that none of this is about money. This is about whether righteousness or wickedness is increased in our lives and in the world around us. Those focused on money actually aren't focused on God. "No one can serve two masters; for either he will hate the one and love the other, or he will be devoted to one and despise the other. You cannot serve God and wealth" (Matthew 6:24).