The Government of Egypt has ended visa-on-arrival as of 15 May 2015.
All persons MUST have a valid Egyptian visa glued into their passport PRIOR to travel to Egypt.
You can no longer just buy the visa at the airport in Egypt.
If you attempt to board a flight without a visa in hand the airline is legally allowed to deny you boarding until you are properly documented (ie. have a visa in your passport).
Click here for Egypt visas.