Airfare One Way from Europe to States

I'm interested in booking a repositioning from the states to Europe. Specifically Celebrity's repositioning cruises either from Florida to Europe or Europe back to Florida.

Is it cheaper to just book the one-way fare along with the cruise, let's say through the Celebrity site, or book the one-way air separately?

Thanks Cruisemates!

[Darcy]

I'd price it out both ways. Sometimes its cheaper to buy roundtrip air and then just don't use one leg of it.