My belt snapped just over a month ago as well, i were looking at a £1500 repair bill for orignal Lexus parts inc all other belts and labour too, however thanks to the AA's parts and labour warrenty they made a £500 contribution, and in my experience, the IS200 is NOT a non-interference engine, mine broke when idling and was only attempeted to start twice but i had bent valves and bent pistons.
Looking forward to the news on the rollog road though, im running on LPG and am curious to see how the figures are affected