Its always a good idea to get friendly with a member of bar staff.
We got to know the guy at dome and we got some free drinks, hope he is still there. Also its a good idea to oredr your drinks in spanish, all i can say is ive never spent £10 an a drink anywhere, I think the most was 1500 psts in Pacha 2 years ago. I must admit I don't drink that much once i get into the clubs apart from when i'm in Space.
I know that 2 yrs ago I bought 2 Double Vodka red bulls from the inside bar at Space several times and it was about 2500 psts whcih i thought was pretty good. I always use the inside bar at space as it isn't as busy as the bar outside.