[Fnoord]

A SLA would. I would just use multiple backups. One self-hosted on-premise and two off-site. Then the two off-site can have egress costs. Wouldn't matter. The self-hosted one would be the primary one to backup from. And it is going to be solid, usually. For example, a Synology NAS would suffice.

[fulafel]

I think nearly all SLAs just give you discounts on the service's bill.

Eg if your service vendor costs you 1000/month and they have a 10-day outage and you lose 10000000, they will credit you 1000 best-case, or maybe 1/3 of that (since it was up most of the month).