Maybe I don't know what I'm talking about, but what does the mining difficulty have to do with the price of bitcoins? That is determined by the supply-demand ratio, and since the supply is fixed (well, it increases over time but at a steady, known rate), the price is basically determined by demand. If more fiat currency is converted to BTC, the price goes up, and if more BTC is sold for fiat currency, the price goes down. You can watch the bitcoin charts and see the fluctuations sometimes after large movements of currency. The ASIC processors will change mining difficulty (if they ever come out), but that will only affect the miner profit margin, which is negative right now. After the reward halved, they started losing money, because they spend more on equipment and electricity then they get back through the reward. If it isn't profitable, then some people should leave the game and mining difficulty will go down, costing less, until it's profitable again. That hasn't happened yet. https://blockchain.info/charts/miners-operating-profit-margin