I've been paying a fiver a month by direct debit since I joined. I have never been asked to pay a lump sum. It does not ask you to pay a lump sum on joining and hasn't for a long time now. I've been a member for six years now
I personally don't think people are buying a vote for a fiver. There has to be a balance between people who can pay a lump sum and people who can't afford to.