Finally, after a lot of time waiting, I signed for piano classes. I will be paying 33€ monthly, for one hour weekly of piano on Monday, one hour of choir for adults on Tuesday, one hour of music education (you know, theory of notation and stuff) on Wednesday, and an hour of choir for kids on Friday. I think it's a good price.
Thanks for your replies.Well, Alex, I'm in a non-official place for people of the town, a place that teaches lots of things, not specifically music, in Corroios.