just remember in event of a claim on a trade policy not only will you get trade value on your car but you will also have to prove you have premises that you trade from and will have to have reciepts etc... to prove you are actually a trader
my traders policy is £4500 a year but has all my business, tools building cover plus public and workers liability plus the few times ive had to claim have been sorted no problem and quickly, whearas i have friends with "cheap" trade policys who have had no end of struggles with claims
you get what you pay for