"If all you want is dust then go there, scoop it up, come straight back. No commercial justification for MANNED flight or for a SCIENCE mission, imho..."

If all you wanted was say 1 tonne of lunar dust, you probably
do it right now, for about 500 million dollars or less.
If total cost was 500 million dollars then that equals $500
per gram.

How much market is there for lunar material at $200 per gram?

Gold is selling currently at around $720 troy oz
1 gram = 0.0321507466 troy ounces, so gold selling for
about $23.15 per gram

If you mining 100 tonnes of lunar material per year and did this for 10 years, resulting in having 1000 tonnes of lunar material on Earth still means it's one of rarest substances on Earth.
A 1000 tonnes at $200 per gram is 200 billion dollars.

If there was rocket fuel for sale on lunar surface at a very cheap price of $2000 per lb.
You could probably mine 1000 tonnes of lunar material over time period of 10 year and have gross sales of around
50 billion or less which means lunar material on Earth would still be about 3 or 4 times the price gold. If you did this for a century, you could still have lunar material worth
about as much as gold. And at the point where lunar material is selling at the price gold, *some* lunar samples
which were sold in the first year or so, could be worth, 10 or 1000 times per gram of the price of gold.

And if lunar samples were at $100 to $200 per gram, one would have a certain tonnage per year which would be "destroyed"- used or lost. And as the price of lunar samples got down to the price gold, one could have hundreds tons of lunar material per year being "consumed" as in destroyed, "used", "eaten", "wasted", lost, or "disappeared" somehow.