I agree with guys who tell to invest 100$ in ICO. But they might be risky and you should be careful nvesting in one. For now, I can suggest you to learn more about upcoming pre-ico in November MiraLab.io. It's a right choice for you because the minimum investment is 100$. Just start trading with this small amount and you do not get risks to loose a lot money. If the Mira project get success then you can generate profits. Learn more about it and make your choice
Yes, you are right. 100$ I think is not a great value, but you will not have a big profit with that sum. Anyway its a good way to start, to understand what ICO is and dip into the world of investment. Moreover trading right now is much more risky then ICO. And for me, Mira looks potential, I like that they want to support different types of coins =)