The units of evil are accumulated by IP bans. That exit node was probably used by multiple nuked spammers thus it accumulated this fee. There's nothing else to do but try reconnecting or pay the fee.
The evil associated with an IP also decays over time. So even regularly-abused IPs such as Tor exit nodes shouldn't have super high fees (>$10) unless they were abused recently. However, once you've registered an account, your evil score will not decrease, and you must pay, be whitelisted, or abandon the account.
Fees are often less than $1 (see the inputs of this transaction), but they can be more if the particular IP you're using was banned fairly recently.
The forum makes more money from 2 hours of advertising than from a whole month of registration fees. It's just an anti-spam measure.
