If you spend $100 on everything, you will eventually replace some or all of it, spending more than $100.

Then again, you can get an ancient sidewall generator cheap. I bought a few off ebay, and they work! They are quite reliable, but they are noisy, and the drag is noticeable.

I spent about $160 on my setup on my Bianchi Volpe, which is pretty economical. The good headlights are really, really good. I do not notice the drag that the dynamo hub introduces.