Well, if you want to premarket my idea with your non-premarketed concept:

We just have a whitelisted (write-protected) relay, but we allow anyone to send zap events. And I've set a sat lower-threshold in the new client that displays the zap comments in the replies, as if it were a kind 1 or 1111 reply, but with a ⚡ icon on it.

So, you can pay-to-respond by putting your message into the zap. We moderate the relay, so if you put something horrendous in the zap message, we delete the event and you lose your money.