How to keep the website safe?

One idea we have to keep scammers, spammers and fake accounts out is for members to pay a nominal fee (€1) to join? I feel that this would be very effective at achieving its purpose but I worry that it would also be a huge barrier to genuine people joining.

A (nominal) joining fee would also has the added benefit of making the sign-up process automatic rather than having to wait for admin approval, since if you pay you are in! I think that a huge frustration is that when you decide to join you are motivated to spend time on the site NOW and don't want to wait for an admin to click a button.

A €1 joining fee wouldn't be a source of revenue - we would pay at least 50% of it in charges and tax; 50c to become a member for life is peanuts.

So, I'd love to have some reactions to this idea:

Would you pay €1 to join this group if it helped to keep it secure?

• I would definitely still join: it would even be an incentive
• I would probably still join
• I probably wouldn't join
• No way would I join