The projected costs (mining of ore for combined gold and antimony) are detailed in the report first issued January '09 (then revised June '09, revised again July '11). I don't recall the exact numbers. One estimate from 2010 used total costs of around 24% of gross (so Net Value = 76% of Gross Value).

The value and SP projections I made in the spreadsheet use an assumed factor of Net Value = 60% of Gross Value, probably a little low.

If you use Net = 65% of Gross, that's a safe estimate, IMO. Remember, we have some extraordinary overhead costs (IMO, put on us by others).