How about figuring the amount of new cash entering the bitcoin economy compared to newly minted bitcoins? Since the start of the year, the market cap has risen about $355 million. Divide that by 68 days, and we get an average of $5.2 million entering the bitcoin economy each day. Divide that by 3600 newly generated bitcoins each day, and you can assume that that amount of cash entering the economy can sustain a price of $1444/BTC.

Granted, at this time, a lot more than 3600 bitcoins are being sold each day. At the same time, not all miners sell everything they mine. Eventually, those with large amounts of bitcoins will drain their supplies and not be as willing to sell as many.