I'm planning to arrive to Madrid soon and make a short 3-4 day trip to Portugal (Lisbon+Porto). Can anyone point me to some budget means of transport (hitch-hiking is out of the question) - websites, company names, anything would be welcome.
More specifics:
I can drive but there will be only 2 of us going so I don't think it will pay off.
Ideal option would be getting there overnight so as not to lose the day on travelling.
International trains can be expensive so I'd rather not take them. I checked flights - Ryanair Madrid-Porto is around 40 euro but flights have to be booked couple of weeks earlier and I'd rather be flexible until let's say a week before the journey when the final plan gets clarified :)
In many countries there is some kind of a bus service - really cheap one (like meinfernbus in Germany or OrangeWays in Hungary) - which for example offers tickets more cheaply if you book them in advance (and these are really a bargain). Does something like this function in Spain?