Before you lower your car you need to decide the purpose. If you want to slam it, add some camber and try and pull off 'stance' then budget coilovers will usually do the job (just remember you get what you pay for).
If you want to lower for the sakes of just looks, but only by a few mm then lowering springs will be fine (and not very expensive).
However, if you want to do things properly and lower it for the sake of making the car handle better then I suggest you get fully adjustable coilovers. That's what I have and it not only improves the visual sie of things because it's lower, but you gain performance aspects as well.