Conor has the right idea. You can never be too careful nowadays and you need to plan for the worse.
Always make sure you have backups in several places: on site, offsite and offline (USB stick or CD/DVD media). This isn't just in case of your host going bankrupt but also in the case that your data becomes corrupt or hacked by an intruder.
This is crucial since your reputation depends on it. When a customer sees that their data is gone, they don't care why, they care that you didn't take the proper precautions to have it back up and running in a timely fashion. Can't pass the buck here, you just have to watch your back and hold yourself accountable for all possibilities.
Hope this helps.