I'll post this as a top level comment, because I think it is crucial: A few people are saying that it is expensive to run a relay but others have done it for as low as $34/month [1]. So unless somebody presents other proof that it is expensive I would say that those posters are either wrong and trying to mislead us on purpose.
Edit: actually the article links to somebody doing it for $18/month.
Edit: actually the article links to somebody doing it for $18/month.
[1] https://whtwnd.com/bnewbold.net/3lo7a2a4qxg2l