I used to get mine from superior neutraceuticals, who now seem to only stock it in a mixture. I see them cheap at docsimon dot com, never used that site though. They are prescription only in the UK, although it is legal to import them for personal use.
My game suffers from the effects on my play due to tiredness and lack of sleep, that unmistakable 'sag' that sets in. It's really terrible for the game, you're just not in tune with the action or opponents. All of that deficit disappeared with piracetam, focus was always there, clear and sharp. The studies were really positive mostly on people with deficits (ex-alcoholics, brain trauma, etc)...maybe that's me!