Hiya
This is an unanswerable question as there's just too many variations and permutations. I've renewed my policy for an 03 BMW 530d Touring (Wagon) - I'm 34, 3 points on me licence, protected 5 years NCD at £670 for Comprehensive insurance. The American F150 Truck I and me bro share costs a reasonable £980. I was messing about with quotes and had pricing for a 2000 Porsche 911 ( a reasonable £1600) and an M5 (at £1450) a Merc SL55 AMG (£2750) and a Corvette Z06 at £2550.
Meanwhile at the other end, I think for me to insure one of the company smart cars if I had to would be a wallet friendly £220.
The 'general' things for insurance are , type of car, your age and occupation, driving record, area in which you live, overnight garaged or not/security and repair costs -
next thing to do is to phone around to get the best quote you can - try all the big names, Direct line, Norwich Union, Elephant, Admiral etc etc and do check out the local Brokers as well - sometimes they can get some excellent deals .
If you have something that's 'different' I highly recommend Adrian Flux (our F150 is insured through these guys)
Lastly, take a look through the motoring magazines to narrow down a selection of cars to buy and ensure you get a quote for all of them for insurance. The LAST thing you want is to buy a car, get it home and fall over when they tell you how much the insurance will be! - and yes, this is exactly what happened to a mate of mine in the early 90's when he HAD to have a Renault 5 GT Turbo at 18 years old!
Good luck!
DtM! West London & Slough UK!