Your client could auto-zap it when replying if you have a built in ecash wallet or NWC set up. nostr:npub1h0uj825jgcr9lzxyp37ehasuenq070707pj63je07n8mkcsg3u0qnsrwx8 charges you 1 sat to send a DM and it seems to work great. I’ve only sent a couple messages though. 

If you only read from paid relays, you’ll miss out on all the notes from people that can’t afford to pay for the relay. Paying 1 sat to post a reply is much more manageable than paying 50k sats upfront for a relay.