Hey welcome to LOC mate, Im a newbie myself and have taken the plunge and bought a 2000 'W' reg IS200 Sport in the colour Platinum ice.
Im not the best for giving buying advise out but just look for signs of accident damage ec, I dont think these cars rust but have a look anyway (it could be due to poor accident repair if there is)
There seem to be quite a few out there with poor or no service history at all and I think this is a testament to the build quality, Thet just keep going.
I paid £2k for mine and Ive spent £400 so far and will probably have to spend another £200 for it to be as near to perfect as possible....The money Ive spent though is service cost, wheel refurb....Im going to replace one front shocker and have the coolant changed....All this is just where and tare though and it doesnt bother me as its just maintainence and nothing serious.
You wont be dissapointed, Mines the smoothest car Ive ever driven and Ive driven many nice cars.