This firm offers budget bus service from Warsaw Modlin airport to the centre of Warsaw (you'll be dropped across the street from the Intercontinental on Emili Plater), but it requires an annoying bus change at the 'Modlin Twierdza pętla' stop. You pay 1zł for the first portion of the trip and 8zł for the second bus into the city for a total of 9zł. From the centre to Modlin it's only 8zł however. For the schedule visit their website at www.translud.pl.