I'm 28 and at the moment i'm insured on a Mercedes C200 as the second driver for only £200 per Year fully "comp", with Performance Direct, I used comparethemarket to get the quote the day I passed my test ( 10 months ago ).
Have a look at the insurance group the car you are looking for is in and think about opting for a smaller CC engine and see how this affects your quote(s).
http://www.carpages.co.uk/car-insurance/