Paying relayers per note using e-cash tokens... aka Nostr meet Pastebin.

This makes it easier to post using a throwaway account. Relayers should announce which e-cash tokens they support, and their pricing. At minimum there should be a price per kilobyte day of storage (but pricing could be more complicated if needed).

A client then creates an envelope, which could be a regular Nostr note. This contains the e-cash tokens needed for payment, encrypted to the public key of each relayer that you want to use. The envelope also contains the actual message that you want to post.

Relayers can discard the envelope if they wish, so they don't have to store and upload all those tokens.

Something similar can be achieved with just a regular lightning invoice too, e.g. using lightning API keys: https://docs.lightning.engineering/the-lightning-network/l402

The envelope could be delivered over Tor, so it's nice if relayers list a hidden service.

Clients should track that their message is actually relayed. Just reuse the tokens if they're not claimed.