Never have, don't see the point as long as free are around.
It's nice to pay for things that you use. Unless you're often zapping your current relay providers?
Personally I'd like to see actual nonprofits organizations that have freedom of speech as a mission and run a Nostr relay as part of that mission. I'd like to donate to such organizations.
Like hrf?
I'm actually not familiar with them. I see they are a human right organization and that they stand for freedom of speech and expression, but I'd have to dig a lot deeper to hold an opinion about them. Alternatively, there could be an organization, or an organization of organization, which is Nostr-focused and run relays, which is something I have been thinking about (but not something I'd be the right person to start).