Just to give you an idea of how inexpensive transport is - Fuengirola - Málaga by train 45 minutes just 2,60 euros (By bus it's 50 minutes and just 1,70)
Barajas to the centre of Madrid - just 1,60 (?) (Compare that with the Heathrow/Gatwick/Stansted Express)
Another GREAT offer that is overlooked and NOT promoted well is the
www.alsa.es "tarifa plana" for one week/fortnight/month. For just 99 euros you can get UNLIMTED travel on their buses/coaches. When you consider that Málaga - Barcelona is 135 euros return you can see what fantastic value it is - this week I am doing Málaga-Murcia-Torrevieja-Valencia-Barcelona-Torrevieja-Alicante-Málaga .....all for 99 euros!!