I need some help with finding the right speaker/amp system for me...?

Basically i am a teenage boy who is into making music or producing as some people may know it. At the moment i am trying to build up a studio, so far i have a midi keyboard and midi electric drum kit. I also have an alesis mixer and a very bad guitar amp i am using for my drum kit. I am using a computer with cubase software and it is all working perfectly. Now the time has come for me to upgrade my guitar amp speaker set up to a decent set up. For my set up i would like a fairly cheap kit including pive speakers and an amp or even active speakers but i'd also like the quality that a producer needs to make music. I have had my eye on the jbl control series but hav'nt really researched them yet. My budget for this is around �150 but this is flexible, i know this is alot to ask and it is a very small budget but as i said i am a teenage boy :D any answers will be very gratefully accepted and i thankyou just for reading all of this in the first place :)