I called a car service which was twice as expensive as a taxi. Just get a taxi at the airport!

Definitely recommend taking a taxi - it's the easiest way from the airport. I believe it cost us around 40 Euros, but obviously split between 5 that's pretty fair value.

Taxi

We took taxi and we were four. I really dont remember how much it costs. I guess someone can recommend you a cheaper option...Enjoy your trip!

We took a taxi (for 5 of us), which cost about 55 EUR, even though the taxi driver quoted us 40 when we got in. If you're fit and able to carry luggage up and down stairs, though, you could get the Metro to Sagrada Familia station, as it's just around the corner from there. We went back to the airport by Metro, which cost us about 7 EUR each (2.10 for the ticket, plus 4.50 for the airport shuttle).