OK here are some nuggets from an Insurance porfessional.
1. First you can't compare prices across state lines. Each city is rated by it's own risks and insurance laws let alone each state. NC is a "bureau" state, MI is a "no fault" OH has very strange subrogation laws etc
2. You can't compare insurance person to person very easily even in the same sate. Credit is a factor in many insurance prices, as is marraige or multi-vehicle discounts. Home ownership status let alone discounts for having home and auto insurance with the same company.
3. Discount, discount, discount means crap, crap, crap. Discounts are marketing ploys. People love to say that they recieve 40% off because of discounts, but if your rate with 40% off is $500/6months and my rate with no discounts at all is $400 who has the lower price?
4. Insurance comapnies are not loyal to you. Your agent might be. hopefully he/she is. but the company and the people making the claims payment decissions are NOT. It's designed that way. That is why your agent isn't your claim adjuster. The companies don't want you to know your claims adjuster. They want impartiality.
5. Your rate doesn't instantly drop when you hit 25. you have to shop for it. An agent saying age isn't a factor is probably lying to you. When you hit milestone ages (18, 21, 25,30, 40, 55, 75) you should shop your insurance. That's at the least if you want the best rate you can get.
6. It's your money. You can save a lot or you can be lazy and go to one or two people to find your insurance. As an agent i love it when someone comes to me and i can tell i am their only stop. i still give my best rates becasue that's my long term business plan, but not everyone is as focused on the long term. In the end how you shop determins how good of a rate you will get.
if i think of anything else i'll drop it in.