deadhunter

hey guys, first of all first time owning a yamaha, i have not been riding a bike for long(about a year). quick question, i recently acquired a YAMAHA FZS600 (2000) and one of the front discs has a slight gauge in it, it brakes absolutely fine with no issues. my question is if i am getting them replaced, is there a specific size i need to get, or can someone point me in the right direction for a low budget decent set, as i would not just buy the one i would replace both including the pads. many thanks in advance