I think if a person is interested in Bitcoin investment and he has only 30$ then best option will be that he should use these money to get some experience in trading rather than expecting huge profit from them. Because profit from Bitcoin investment depends on how much amount you invest and how much percent Bitcoin price goes bullish, if you invest 30$ and Bitcoin price goes 10% the you will get just ten percent which will be 3$.
So when ever he got some big fund from different source then you should welcomed him in really world of trading where he can expect some bit from his investment..