Speaker collapsing is terrible thing to waste
All bands should have liability insurance. If you hire a band for an event, there are two reasons you need to insist on an insurance certificate.
I highly agree...I've never had to do that, but OK. Talk to your homeowner's/renter's/car insurance agent. Whatever it costs you, roll it into the bid for the job, plus an administration fee— $75 for the hour of messing around on the phone it's going to take. There's no way you pay for that out of your original contracted pay. Write a new contract with the updated amounts.