@bluebird,
There are a few more variables to take into account such as shares out, quality of the asset (grade), location, regional activity, and many other fundamentals. Then you also have to account for market activity, macro and micro, sectoral/asset class activity, etc.
I like the $2-4 target though ;)
Rule of thumb: In situ value (value of mineral in the ground) should be around $100 per ounce of gold in the ground, on the low end.
Total ounces times value = target market cap.
Market cap divided by shares out = target share price
Hope this helps.