so, still no takers on the gold/silver thing?
i am imagining it like that:
miners would register a bitcoin adress related to an account on my site.
they could chose the product they'd like to accumulate (choices may include 1g gold bars, krugerrands, 1g silver bars, 1oz silver coins... whatever).
so every time the actual factual price of the product is reached, the system buys one for them.
if they would like to have their stuff shipped, the just tell the system and the moment the calculated postage is reached, voila, stuff is sent on its way.
is that kinda how you wanted it to work out?