Here is an article dealing with the challenges involved in valuing a small miner's in-the-ground assets. I have no expertise in this area but found this quite informative. The author shows how many factors influence the market beyond just the straight estimates of metal in a property. The shares of three companies are evaluated to determine whether the market is properly recognizing all the up and downsides of each company's shares. Not sure whether this has any bearing on ECU.

Here is the link:

http://www.stockhouse.com/Columnists/2010/Feb/1/Valuing-a-junior-miner-s-gold-in-the-ground

And here is the author's closing statement:

Bottom line

We often get asked what an Inferred, or M&I, or P&P ounce is worth in the ground. The $20, $30, and $160 figures are only rough guides, and you must consider the reasons why some ounces are given more or less by the market, but they're a good starting point.