The ongoing structural rebuilding of the power industry in the world determines the formation of electric power markets. To the fore, economic factors are brought that dictate the market relations with due regard for reliability of supply and quality of electric power. Market participants sell and buy electric power at the agreed equilibrium price, which, owing to system limitations, cannot be made equal for all of them, and individual (nodal) prices would not be the same for different generators and loads. The authors consider the basic models of electricity markets and the influence of limitations on the nodal prices. The calculations have shown that, taking into account the technological limitations, the generators of cheap electric power should sometimes be off-loaded (or even switched off), the generators of more expensive electric power to be used instead. As a result, in different nodes of a power system differing prices could form.