All my four pigs are insured at a cost of about £35 per pig per year. This is in Sweden, so not applicable to you, I guess... The deductible amount is about £50, and the insurance doesn't cover dental problems, PTS, meds, castration/spaying,nailclipping and a few other things.
I have it mainly to be able to say "go ahead" should one of my pigs need an operation for a cyst, abcess or bladder stones. Those operations often cost about #600 in Sweden, so would be a big cost right then and there.
I know many people don't insure their piggies though, and prefer to set aside money each month instead.