Hi Momo, welcome to the club.
I've maybe missed you but Is it today you are going to see the car??? not the best roads for a first drive of one that's for sure!!!
If you have done your homework on this site there is a few things to look out for, i would deffo take a couple of cd's with you to try out the headunit.
Check inside front tyres for uneven wear.
The cambelt, 60Kfrom new, then every 30K from then on is what is recommended by lexus, this may be over the top, but you dont take chances with cambelts, especially if they are aftermarket ones!!! so i would budget to have this done.
all 2nd hand cars have increased in value recently, IS200 are no different, but i would be looking for some money off as a timing belt, tensioner & idler will set you back upward of $100 + fitting!!
Tell us how you get on bud.