My IS 300 has done over 140000 miles and i havnt serviced it in more than 2 yrs!
At the mileage you are quoting, I would be more than happy to buy that car!
Many people think that milage is a problem but i tend to disagree. Mileage is proof of distance covered and if looked after well, there is no reason why on this engine the car wont do 3 times as much! Its a well tried and tested engine which is used in many different variants of toyota and lexus.
As for timing belt. Its worth a look by taking off the cover above the top pulley (4 hex bolts) and deciding the condition of the belt.
There should be 2 or 3 mm of pulley visible at the front edge of the belt and the belt should be approx 1" thick.
Ive NEVER heard of a belt just snapping and personally think that this kind of scaremongery is for the foolish.
There are plenty of threads on here (with pics) to show what to look out for re timing belts.
As for doing your own service work I for one would highly recommend to do so if u have some practical ability and a fair tool kit or find someone locally with some savvy :winky:
The plugs are a bit of a mare on this 2JZGE engine as the throttle body and few bits need removing first unlike the TT version on the supra.
So to sum up. You go for it mate. Buy the one with the mileage and the history and find a reliable service mechanic who knows what theyre doing.
It is not necessary to pay Lexus in excess of £100 per hour labour charges trust me so Dont dither over this one.
If you like it, then just buy it mate. :)