Hiya
I work in insurance, and as everyone has said, pricing can depend on lots and lots of factors - age, sex, location, where the car is kept, the car itself, etc etc. This all feeds off real statistics from past claims.
Unfortunately in the last couple of years due to a combination of lots and lots of weather related claims, as well as a massive increase in fraudulent claims (the kind where another 3 people miraculously appear to have been in the car at the time and all claim for various injuries), costs have risen massively for the companies themselves, and prices have had to go up to compensate.
In fact I'm losing my job at the end of this year as they are shutting our office to recoup costs.
Best thing to do is to ring round specific companies - don't always rely on internet quotes as you can often get it cheaper on the phone.
The other thing to bear in mind is each company or brand (as lots of companies have several brands) have their own target audience - so prices vary depending on the type of customer they're trying to get in.
Hope that helps a little x