Spain's enviable, high-speed AVE train network is introducing a Madrid-Valencia route on December 19. The train, which speeds as fast as 205 mph, will cut the journey from three hours and 50 minutes to 95 minutes, while only raising the ticket price about $16—from $107 (€78) to $123 (€90), raileurope.com. (The current Alaris train will still be available at the cheaper price.)
Even so, high-speed trains can't beat European low-cost carriers when it comes to pricing. Ryanair has a 55-minute flight available from Madrid to Valencia for $40 on December 19, according to Kayak. But consider whether you really want to subject yourself to Ryanair's no-frills service and notorious fees—and the added hassle of checking in and clearing airport security.
For more comparison pricing of train and flight routes in Europe and Asia, check out The Fastest Trains on the Track.