Priceline.com: Non-Stop RoundTrip Flights from Miami, FL (MIA) to Washington, DC (IAD) from $132

-- Departs Miami (MIA):
** Sept 12, 14, 19, 21, 26, 28; Oct 5, 10, 12, 17, 19, 24, 26, 28; Nov 2, 9, 16, 30; Dec 1-2, 5-8
** Returns: most Mondays, Tuesdays, Wednesdays and Saturdays
-- Departs Washington, DC (IAD)
** Sept 5, 6, 12, 13, 19, 20, 26, 27; Oct 3, 10, 11, 17, 18, 21, 24, 25; Nov 1, 7, 8, 14, 15, 28, 29; Dec 5, 6, 12, 13
** Returns: most Tuesdays, Wednesdays and Thursdays