If any IT genius on the board can work out a real-time switch-over AC backup scheme with no data loss, I am sure many would pay for it.
This has already been done. You can keep two live servers, it's called failover clustering. If one goes down, the other node kicks in and users don't notice a thing. You can also do things like a live migration. MS made this affordable for small businesses by offering Hyper V Replica even on their standard line (Server 2012) of OS's.
However, the configuration can be confusing and is best left to the Pros like Indy or James. If you need an in house solution, it's best advised to contact someone who is familiar with the setup. I'm working on a way to make local servers easy to setup with little to no input required from the end user. What you mentioned above was also another thing I was working on.
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