With insurance, you pay up front, or you pay over time. The better you build your network, the lower your cost to insure it.
In my day job, I work for along side an IT consulting firm. They specialize in reinsurance companies that live and die based on their IT infrastructure. If the servers are down, they can't run their risk models, and can't quote the business. They can literally lose millions per hour if their servers go down.
As a result, they generally buy what seems to be an overkill network for the size of the company. Can you say over $100k per employee? These guys are the insurance companies for the insurance companies - possibly the smartest bunch of people I've ever met.
It's all a matter of the risks you want to cover. Either spend the money to build the system right, or pay for insurance in abundance.
Errors and Omissions is probably your best bet to start. But spending more on your systems and procedures will save you the most money over the long term.
(in looking over this post, I think I might have missed the point completely. Whoops. Too late to delete )