PMP Member Benefit

Hi, I am planning to submit my PMP application online to appear for the certification examination. However, it suggests that if I become PMI member, i will have to pay less fees for the exam. My question is - what is the general practice here? Do most of the applicants first become a PMI member and then submit the exam fees separately (which will be less)? And, then keep paying the fees every year to retain the membership? OR should one time extra charge (being a non member) is good enough to appear for the exam and then there is no need to become a permanent PMI member? Can someone please advise how does it work and what is the recommended way here?