How do you get the currently selected <option> in a <select> via JavaScript?
This will do it for you:
var yourSelect = document.getElementById( "your-select-id" );
alert( yourSelect.options[ yourSelect.selectedIndex ].value )
The .selectedIndex of the select object has an index; you can use that to index into the .options array.
var payeeCountry = document.getElementById( "payeeCountry" );
alert( payeeCountry.options[ payeeCountry.selectedIndex ].value );