I'm thinking of building a mining machine, and am trying to figure out if it will be profitable. I've used this: http://lorelei.kaverit.org/cgi/calc.py
to calculate the profitability based on today's difficulty and compared with today's BTC/USD rate. But I would really like to see how the [BTC/USD rate]/[difficulty] has changed over time so I can try to guess at future profitability. I can find graphs for each (difficulty here: http://bitcoin.sipa.be/
and BTC/USD charts from MtGox), but not the raw numbers. I need to find the raw numbers so I can compare them and make a value/difficulty graph.
Does anyone know where I can get the raw data for difficulty and exchange rate? (or better yet, a graph of the ratio that someone has already put together)