Price is usually determined by producer greed because producer greed causes prices to consistently be set as high as possible. This is usually constrained by market competition, which limits how high they can be set. In rare cases, prices are set low by consumer greed.
A high price has a direct cause: the person in charge of setting prices set a high price. A little less direct: that person is incentivized to set prices as high as they can. Much less direct: there are currently few competitors due to avian flu; we have one of very few chip fabs that can make the widgets; our customers are locked in; our customers signed contracts allowing us to raise prices but forbidding them from cancelling when we do. Greed is always one of the more direct causes of high prices. The fact that capitalist markets use greed as an integral part of their normal functioning does not change this fact.