I've factored in Difficulty changes and the rewards that come with that but I'd like to try and factor in price changes too.
Does any one know the formula that PBMining use to calculate their price per GH? i know it based on difficulty, same as their reward payouts, but not much after that.
A good strategy for buying hash power is to purchase right after a difficulty change. There is not much more you can do than that. As far as our prices go, we sell for what we think we can get on the market, or what rodeoclown tells us to.