You can trust your own hardware more than someone else’s hardware. Everything can go bad, but if you physically have access, it increases the probability of recovery. (Since you care more) Usually one copy where you have easy physical access and sure other than certain people cannot access this room (has all the required indicators and alarms in case of high temperature etc) another one within the space of governmentally approved area (usually this area has the least probably of seeing natural disaster) should be enough. Costs? Data security cannot be subject to tradeoffs. Usually two people own two physical keys to the backup machine, without one , the machine should not allow any access (in case one of them threatened to give up the data). you ought to keep the keys in secure place.
It’s firstly information security engineer’s responsibility to take care of the Information security.