United Airlines has Los Angeles LAX to Barcelona BCN priced as low as $414 round trip for flights in October. Iberia’s Level Airlines is as low as $376 round trip. I do not currently see these low ticket prices for departures any other month.
Expedia ticket United Airlines/Swiss Airlines $426.52 round trip
Sun Oct 7 Los Angeles LAX – Washington IAD – Barcelona BCN (United)
Wed Oct 17 Barcelona BCN – Zurich ZRH – Los Angeles LAX (Swiss)
Level Airlines  Los Angeles LAX – Barcelona BCN – LAX
$376 round trip Sun Oct 7 – Wed Oct 17
