As a startup, generally your secondary backup could literally be an external hard drive from best buy, or an infrequent access S3 bucket (or hell, even Glacier). No excuse, especially when "dealing with Fortune 500 companies".

Triple hosting costs?

Literally just push a postgres dump to S3 (or any other storage provider) once a night as a "just in case something stupid happens with my primary cloud provider". It'd take a couple hours tops to set up and cost next to nothing.

Most of the costs aren't from storage space, but compute power. We aren't talking about duplicating the whole infrastructure, just backing up the data. Disk space is dirt cheap.

Also, by "two places" I meant the live DB and one backup that's somewhere completely different. My wording may have been confusing.

They did have backups. Thats why I asumed you meant double backups. If you do cold storage you should have 3 copies due to possible corruptions. Sure tape drives are cheap but someone also have to run and check the backups.

That seems like an odd cost increase. How do you figure it would lead to a tripling of op costs?

I would say that it doubles the cost of backups, but using this math, we start with one copy plus one backup, and add a second backup; that means only a 50% increase.

Also a secondary backup doesn't need to be in hot storage. Coldline or Glacier or similar can easily be a quarter of the price per GB.