People keep asking me that question. Unfortunately it is very hard to put a fair price on it, since it has absolute no underlying assets to evaluate.
I keep telling people that there is only one calculation I run in order to create my own expectation, and that is: Think about how much of the world's financial system you believe will run on bitcoin, then get how much currently runs and multiply the current price for that factor.
My reasoning is quite simple: Bitcoin has no intrinsic value. Thus its price is purely regulated by supply and demand, and the demand will grow proportionally to the share of the financial system running on bitcoin.
One could argue that Bitcoin has some intrinsic value due to its adoption. Even though I agree with such a statement, I consider its value to be zero, since it is increasingly easy to switch between cryptocurrencies.
The Howmuch.net website has posted this nice image:
That's a very good way to put it into perspective and help anyone create their own expectations.
Cheers !