Yeah, that feeling of not knowing if the price is low or not is....uh...kind of the point. If you knew that the price was at the bottom, this investing thing would be easy and everyone would be rich! The world doesn't work that way. And predicting the price of Bitcoin or other crypto currency is very difficult, it's impossible really.
The best thing is to decide if you believe in the future growth/value of the coin then you should buy some, today. That's your starting point, your cost basis. If the price goes down but you still believe in the future growth/value, buy some more. And you're on your way.
That's it, man.