what is a realistic valuation for lynas?

I have held Lynas stock since 2007, bought as high as $1.50 and as low as 20 cents. A fair amount of trading that has not been so successful, but recently as the price of the stock has fallen, I decided to buy more rather than to sell and face buying back later at a higher price, which was my usual (bad) method. But the question now, as we approach production and actual cash flow, is what would the stock really be valued at? I just did a check on perhaps the basic materials benchmark, BHP Billiton, and to keep things real simple, checked its price to sale ratio. It has a market cap of 200 billion and its sales are about 70 billion, its P/S ratio as shown on the finviz website is 2.83.

Lynas's market cap is a little over 1 billion. So in order to have a P/S ration like Billiton, it would have to sell about 430 million worth of RE, right? Well, that isn't really in the cards for a long time to come. So how does one really determine, at least over a year time frame, what Lynas' valuation, and therefore share price, is? Can anyone help out on this question?