Not the first time either. Remember the esb substation fire thing last year!!!
It would depend on what was affected I imagineUpdate: Power has been restored but no sign of sites yet. How long for a full system reboot to take effect do you think?
Is running 10 sites with a target of 100% uptime expensive?
That depends.
This site and my other ones are on a couple of my own servers.
The only time they go offline is when I do something dumb
To answer your query - costs would vary depending on who you ask and what they offer you in return, but if you are doing serious business online then a dedicated server with a reliable hosting provider is the way to go