And now, futur's zeppelin.social is a Bluesky-compatible AppView with the complete history - 16TB of data, so $200/monrh ... not dirt cheap but not horrible (for comparison, chaos.social is $400/month with 6K active users, and infosec.exchange's admin Jerry spends about $5000/month on the various instances he runs).
https://whtwnd.com/futur.blue/3ls7sbvpsqc2w goes into detail on the project, and https://bsky.app/profile/bad-example.com/post/3lscmaacjcs2j is an example post from the (non-Bluesky) deer.social client to thje (non-Bluesky) zeppelin.social AppView via the (non-Bluesky) Blacksky atproto.africa relay. Impressive!