Sadly, but it happens. There was an ad in the web. Those folks must be in dire straits. I hope I never get into a situation like that. But even if I do, I don't think I can ever sell my children.
Yet, God did not sell His Son; He gave Him up freely. And for what? To pay for our wrongdoing. That's a very unprofitable transaction. Here we are wallowing in selfishness and utter disregard for God and He gives His Holy and Loving Son just to give us another shot at eternal life later and to a more meaningful & transcendent existence right now. It is what God does.