its a night mare! ive got a good broker so long as you dont want to insure you vehicle for big money. i tried to buy a 90 with loads of modes etc and declare them all and insure the vehicle for 8k, but this seems a huge problem, no insurance company want you to go off roading in a car worth 8 k and they wont insure it third part f+t!
if you want cheap insurance, buy a series 3 or an early 90, insure it for no more than 2k and have a limited milage policy.
My brokers are frank pickles, they do kit car insurance (ideal for ibexs) and off road insurance for your average play toy 90. For 12 months it cost me 400 quid with any mods so long as the vehicles value is less than 5k and there a limited milage. im 22 which i think isnt bad considering.