Seem to recall 12 euros as an entry price. Menta's the biggest of Alcudia's discos. Music varies according to themes, but it is strong on salsa disco style - or used to be. Menta is a popular place with the local crowd, more so than Bells. There are two other discos, one close to Menta at the Magic Center, known as the Magic Disco, and Atoms. Atoms is also popular with the locals. Magic is looking to attract a more international crowd, as I understand it. The Magic Center has a number of music bars as well, a new one called Absolut is pretty good.
Hope this helps.