yup. tell them you already have a warranty, its represented by the badge on the front of the hood. welcome to priuschat!
It's not a "scam" as defined in the dictionary, you'll get the coverage you pay for. However, it is a scheme that definitely favors those who sell them over those who buy them and are generally not recommended, especially for the Prius. The Prius has a pretty solid track record of needing minimal repairs until well after 100,000 miles. So the thinking is that if you can afford the cost of a warranty, you can afford to take the chance that nothing major will break that isn't covered by standard warranties. If you are interested, I'd be very wary of a 3rd-party contract. Friends who bought those say they never will again, dealer warranties only if they buy one in the future. I don't recommend one way or the other. I got beat for $5,000 on our van because I didn't buy one, but that's not necessarily a reason to buy one in the future. I'm still ahead financially by not buying them for the 6 new cars I've bought over the years.
It's a cold call. IMO, it is almost guaranteed to be a scam. If they are calling someone on the Do Not Call List then they are even less reputable.