The price of oil is manipulated by a small elite of businessmen, politicians and bankers. Remember "Peak Oil" a few years ago when the price rocketed for no apparent reason ? Now we're in a glut.
OPEC was created to keep the price artificially high for the benefit of the producing countries, hence the oil shocks of the 1970s. The cost of production has little to do with it as the current price is well above what it costs to get it out of the ground.
The real factor is how much the producers need to sell it for to balance the national budget, most of the producing countries have little if anything else of value to export.
You would only see a true price without OPEC and its production quotas. If each producer pumped out as much oil as it liked and sold it on the open market then you would know the true value.
The free market would decide the price based on production costs, demand and the price of other forms of energy. This price would be well below what OPEC members need to keep their oil dependent economies going.
Cartels are illegal in most first world countries, try setting one up in the US to control the price of bread and you will end up behind bars.
OPEC get away with a business practice which has been outlawed for good reason.