If you are a Costco customer, I think you are crazy not to buy their home and auto insurance from Ameriprise. Let me give you two reasons: (1) next time you are in Costco look around - do any of these people look like hot rodders? That would make their insurer feel like they could afford the lower prices Costco would mandate(2) If you have a claim with Nationwide et.al. it's you against them, in an adversarial relationship. Because I am a long time Costco member it's me and Costco against Ameriprise.
I have been down this road before. If necessary, lawyers from Costco will back your claims against their suppliers. It happened to me.
I pay $480/year for full coverage on a 1995 Monaco Dynasty 36'.