80k is not much, nothing in fact on a Lexus
If this was from a garage I would take it for a drive, this is one hell of a car
http://www.autotrader.co.uk/classified/advert/201506044034717?page=1&search-target=usedcars&quicksearch=true&channel=cars&onesearchad=used%2Cnearlynew%2Cnew&radius=1500&postcode=so152sn&sort=default&model=ls_460&make=lexus&logcode=p
As for the ISF, the whole issue of discs, calipers and tyres, pads etc are the main issue. Paint work can be done in a shop. Even to get entire discs/pads can be got much less than Lexus prices from ebay etc and get a indy to install.
I find the ones priced for 20k+ far too much for a 08.
keeping in mind what you can get in a ls460 for example.