This is a real problem, but not as big as Libertarians like to make it out to be. Additionally there is a tendency to ignore the very large command economies within our market Surely the command economy within Wal-Mart is at least as large as the USSR was, and it appears to have just as many inefficiencies, and absurdities generated by perverse incentives and miscalculations.Because it is not the state it manages to do away with the most egregious cruelties of a planned economy, and is definitely preferable to a state planed economy, but it's also probably not the best we can do.
Spend a bit of time studying Yugoslavia and the ideas of http://en.wikipedia.org/wiki/Workers%27_self-management if you're interested in non-anarchocapitalist solutions to the calculation problem