The best fare I can get from Lubbock to Cozumel right now for late August is $414.13 RT. $236 of that goes to the airline, the rest is taxes & fees...
Mexico Tourism Tax Derecho No Inmigrante (UK)$37.99
US International Departure Tax (US)$42.20
United States Passenger Civil Aviation Security Service Fee (AY)$11.20
US Passenger Facility Charge (XF)$13.50
Mexico Airport Departure Tax Tua International (XD)$46.05
United States APHIS Passenger Fee Passengers (XA)$3.83
United States Customs User Fee (YC)$6.52
Mexico Immigration Fee Dsm (S1)$9.84
United States Immigration User Fee (XY)$7.00
Before departure taxes were included in tickets, there were always broke kids with paid tickets begging money to leave.