ok so...
it's a bit of an unwritten law, but basically, if you live here, you normally NEVER pay to get in anywhere. there are very few exceptions to that rule. over the last few years I've normally paid entry to about two events per season. the longer you live here, the more people you know and you then either get a season pass, guestlists or they simply know you at the door and let you in. of course if you're not directly working in the clubbing industry it's not as easy, but if you are interested in nightlife you'll always have a few contacts that help you out. as I said there are a few exceptions, for the busiest parties in general (say both david guetta parties), and especially in peak season it's sometimes not possible to get in for free, but mostly it's the parties we avoid anyway.
as for drinks, that's a different ball game. again, the more you go out, the more bar staff you'll know who will sort you a free drink every now and then. or then you know the promoter or the club owners/managers and they mightl give you some drink tickets. but while locals normally get in for free as explained above, we always end up buying a few drinks when going out (and at no discount). which, considering the wages you earn in spain, still works out pretty pricey.
in a nutshell - we normally don't pay to get in but spend more on drinks as in most other places so we still spend money!