Heterogeneous beliefs, price dispersion, and welfare-improving price controls

We consider a search market model where agents have heterogeneous beliefs about the distribution of prices. A suggestive example shows that Jevon's Law of One Price and standard welfare results are not robust to small heterogeneous errors in beliefs. In particular we show that a price ceiling above marginal cost can reduce price dispersion and improve welfare (by lowering aggregate search costs) without decreasing quantity supplied. These results are broadly consistent with the empirical evidence.