What happens if something goes wrong 4 months into the rainy day fund? At $30 a month, you've saved $120 which isn't enough for anything. If I've paid $50 a month for 4 months I've spent $200. and can be covered for $2, 3, 4, thousand dollars plus...
Even at $600 a year, I feel insurance is well worth it - even if I never use it.
