Good-Person
Captain Junkie
When it comes to investment and it happens to be that you would be the one running it,it should be a business you are passionate about,and not just a business you see others doing and they are making profit from it.Because innovation and how to stem the tide when things becomes really complex could be a factor to determine if you will still be in the business.
I think that investing $100 is a good amount because it could possible allow you to make some money if the trades go well. But it all depends on the markets.