Put a number on the price. Put a probability on the likelihood that for that amount we can prevent a hit.
Only then will we be able to decide whether it is "cheap insurance".
Pretty stupid way to do the math. Tell me whats the value of saving humanity? Care to do that calculation? And don't compare it to "Global Climate change" or any other boogieman. This is as real as tommorow. It WILL happen. It's the one type of planetary disaster we can actually try to prevent.