What factors can be looked at in order to come to a fundamental valuation of Bitcion?
Recognizing that Bitcoin has no INTRINSIC value, we look for its USE value, so to speak. The primary value of BItcoin is the reliable and indefeasible transfer of property title (money) between two users. Ever since the first use of the Nakamoto protocol in Jan 2009, there has been a proof-of-concept that has remained valid for almost five years and continues to function through extreme volume and market volatility.

This proven ability for reliable performance is the principal value of Bitcoin. Were it to be compromised, or made to fail massively, the value of a bitcoin would collapse, until it could be repaired, or perhaps to never recover. 

Other subordinate values-in-use can be analyzed in like manner, but as long as this primary value is intact, the price of bitcoin will continue to rise as it will continue to be useful, and thus valued for its use.