Postal prices going up for express, priority mail - Yahoo The cash-strapped U.S. Postal Service is raising rates for its more profitable express mail and priority mail shipping next year, part of its efforts to stave off bankruptcy. The new prices, which take effect Jan. 22, include the introduction of a new flat rate of $39.95 for overnight express mail boxes weighing up to 70 pounds that are sent domestically; the flat rate for express letters is being increased separately to $18.95. Previously, prices for the overnight service were $13.25 or higher based on package weight and distance. The new prices amount to an across-the-board increase of roughly 5 percent in postal shipping services.