I've done quite a bit of looking around re: 433 Eros's composition. I have found very little to suggest to me that there's large amounts of valuable minerals there. Can you cite someone that's done a composition extimate? This: http://www.psrd.hawaii.edu/Feb02/eros.html suggests such estimates are spotty at best, since the formation of the object hasn't even fully been agreed upon.

I'd welcome the evidence about precious metals coming from collisions, that meshes with some of my understanding of the early solar system, but would be glad to know more.

Does that estimate take into account the way such vast amounts affect the price curve? I would think that the gold price will fall if it is available in abundance.