Madrid and Barcelona direct – €39.99 each way all in
Budget Airline Vueling is currently running an Autumn sale:
Conveniently, Vueling flies direct from Malta to both Barcelona and Madrid.
While the sale fares (“from €34.99 each way”) appear not to apply to flights beyond March 2014, there are a number of seats available in April 2014 (and unsurprisingly a few in March 2014, too) at €39.99 each way (so €79.98 total return).
Don’t forget that you can earn Avios (redeemable on BA flights) on Vueling flights.