I've been noticing for a while that there doesn't seem to be a clearcut (interoperable) way to determine whether a given relay requires payment to post there or not. If you do a lot of manual digging and searching you can figure it out on a relay-by-relay basis but that seems unacceptable from a UI/UX point of view unless we (devs) want nostr to be geek-only.

I think for this issue what's probably needed is some kind of push to make both relays and clients really fully implement the "Server Limitations" (at least), and also the "pay-to-relay" blocks from the "extra fields" in NIP-11. So relays need to return those fields and clients need to parse those fields and if the relay has `limitations.payment_required: true` then clients should display that somehow so that it's easy for a user to know whether they can post to a relay right off or whether they need to do something special first (pay, configure POW, etc).

Too early for this now, but it would also be great somewhere down the road if there were a NIP that standardized how to pay for pay-to-post relays in a way that it could be implemented within clients such that users could do it all from within their client with a click or two. In my perfect world, this payment would not be limited to bitcoin / satoshis, but would instead be completely agnostic so that relays could take payment however they want and users could choose from among whatever choices the relay offered.