FYI, y'all: I flew Maya Island Air today and the 50% discount is still in effect. Not sure exactly when it ends, but fairly soon. If you pay cash (Belize or U.S. dollars) rather than using a credit card, you get a 50% discount from the regular fare. For example, round trip on Maya between municipal and San Pedro is just US$30, or $15 each way. That's as cheap as going by water taxi. There is a penalty if you change flights.