Hp laser jet p1102 toner refill

I bought that printer couple of months ago now i need to refill its toner can anyone tell me any good shop from where i can get that refilled as i heard that people will change the toner or do the refill with low grade powder???? and can i do it my self i tried searching youtube on video tutorial but unable to find the video with same model so any good help will be much appriciated.