Trijicon uses tritium with a 12.3 year half-life. Getting the tritium changed out by Trijicon costs about $300.
Get an Aimpoint with a 50,000 hour battery life (that's running time, switched on. About 5 years.). Change your batteries every couple of years and it still wouldn't cost as much as the Trijicon and you wouldn't have to worry about them burning out.