"It's a once-in-a-lifetime event that neither of you will ever forget."

But as plans progressed, they realized that "it is a once-in-a-lifetime event, and you want it to be special."

That sounds like a very reasonable price to me, especially for a once-in-a-lifetime event.

And some who saw it fervently hoped that it would be a once-in-a-lifetime event.

But even if the prices don't fall, paying $500 for a once-in-a-lifetime event is not an absurd extravagance.

But might not this visit halfway around the globe be a once-in-a-lifetime event?

The real reason was simple and uncomplicated: it was her Daddy she wanted to be with during such a special, once-in-a-lifetime event.

But they would be back in time to watch the once-in-a-lifetime event from the perfect seat.

A wedding, unlike a funeral, is not necessarily a once-in-a-lifetime event.

This event is thought to be a nearly once-in-a-lifetime event by meteorologists.