You can get fast tracked on arrival. there will be guys standing there offering the service. While i agree that there are those with a willingness to scam if given the chance, generally speaking you won't have any problems so loang as you are an aware traveler.

Pay no more than IDR150'000 for the fast track service on top of the US25 entry fee. Expect that they will try and get more money out of you by requesting an exuberant fee, however combat this with an offer of IDR150'00.. if they say 'no' walk away and ask one of the countless other guys offering this service.

There are sites now (search bali fast track google) in which you can book this service before arrival should you not want to risk it's availability on arrival.