Your $10m-$20m number is bunk. First of all, there's 9.28m BTC now, not 8.5m. Second, market capitalization does not determine the required money flow for a price change, the depth on the order book does.
Whoops, yes you are right about the 9.28, but that still falls within the bounds of $10m-$20m so as to not disqualify it as "bunk". Notice how wide of a range I gave. Your statement would make more sense if I had claimed, "The price went up $1.75, so that means $16,240,000 must have flowed into BTC."
But the truth is, to achieve a sustained price change, the inflow has to fall somewhere in between the metric you cite (depth of the order book) and the change in market cap. Someone buying all at once will indeed momentarily raise the price as dictated by the order book; that moment will be brief, and in the absence of other buying, that price will definitely not be sustained. And if MtGox has to continue to delay wires of $9999 or smaller, well, that's a pretty far cry from millions. The BTC price did not jump $1.75 based on $9999 or less in buying activity.
for example: you start an alternative like bitcoin. ppl mine 1000 coins, someone will buy 10 for 10 USD.
if he does buy and another is willing to buy at 10. few ppl would argue that now the marketcapitalisation should be 10'000USD. but its actually just 100 USD. this does not mean, that the worth should be 0.1USD.
because real worth is 10 USD if someone wants to pay 10 USD (!!!)
to have the approximative calculation you'd need to look at the trade history of all merchants and sum all buys and subtract all sells at the prices where they were executed.
EDIT: you have to add all capital of the buyside of all oderbooks of all merchants to get a calculation, how much money is involved in Bitcoin-market
this is (nearly) never the current prize multiplied with the existing coins.
easy to do if you want to review the history (since I gather you were not there)
