You need to put the second fading action inside the complete function of the first fading action. Also it would be more efficient if you cache the jquery elements since we are reusing it multiple times
var btn = $('#btn');
var service = $('#services');
var price = $('#prices');
btn.click(function () {
service.fadeOut('slow', function(){
price.fadeIn('slow');
});
if (service.is(':visible')) {
service.fadeOut('slow', function(){
price.fadeIn('slow');
btn.html('Services');
});
} else {
price.fadeOut('slow', function() {
service.fadeIn('slow');
btn.html('Prices');
});
}
});