A new train service started between Barcelona - Madrid on the 20th Feb. The new AVE route has three classes, either tourist, first or club. Prices for tourist class (the one I travelled!) is approx 101€, 1st class 152€, club 182€ one way depending on the time chosen to travel. If a return journey is booked there is a 20% discount on the return journey.There are several trains through the day, roughly every hour. The journey time is 3 1/4 hrs travelling at 300 kms per hr.
For more details see the RENFE website.