I Timothy 6:6-
But godliness with contentment is great gain.
We can be easily consumed with getting. Coming off of Christmas, though he had received many wonderful gifts, including a special fire engine, my son was insisting that he "needed" a play cell phone, because firemen need to have a phone. While I can understand his desire for authenticity, I also know he would find contentment great gain. If he would see that with a little imagination, he could make a phone with a toy he already has, he would be content to play with what he already has and not find a "need" for something more.
We can laugh at the things our children think they need, but so often this is our attitude about life. If we just had *insert something we don't have here*, we would be happy.
There is something in us that knows we need something and most of the time we default to material things to fill it. Here is our chance to show our children, because they won't suddenly become content just because we tell them how great it is, what godliness and contentment look like and just what a great benefit it is to us. Showing our children contentment is a hard thing but if we focus on godliness, or more specifically the doctrine that promotes godliness (piety towards God), then with contentment (peace with what you have) our children will have the "gain" they seek.