Umm, a say who, do what???
Liberty Mutual..... Offers a separate policy, or is this an addendum to your home owners, or is this secondary insurance??? Were you required to carry an umbrella, or a minimum level of coverage? Also your location would be helpful since insurance does basis their premiums by geographical location.
A $250 premium for what sounds like full coverage, exclusively on a $3000 UAV, is VERY difficult to believe. However given the benefit of the doubt, this would tell me a few things, the insurance companies have had time to run analysis on the durability of UAV's & their likelyhood to create personal & property damage. It also tells me that the typical person who decides to go buy a Inspire 1 for their first quadcopter, is one of the more whiny,