Thank you jainla for very infomative respond.
I haven't seen L430 on sale that had visible rust but I just thought if there is some hidden problem spots. It's good to hear there isn't any. It feels like these are better build than other cars :D
I'm not too worried about power steering pump leak, especially if alternator is not underneath the pump. And I believe your and your mechanic's experiences can be extend to all LS430s.
Air suspension is not huge problem to me even it would break, now I know where I can get new or remanufactured air struts and know how much not OEM will cost . I just thought it would be a single most expensive repair to have.
I don't really need a new car but I've dreamed to step one class up (I drive 2002 Volvo S80). I have done some research on 7-series, S-class, A8 and LS430, and LS430 is really starting to grow in me, particularly when reading Germans problems and repair bills! 7-series is full all kind of weird stuff especially before 2005 facelift. S-class, like you jainla said, is also problematic and has it own class of cost of ownership. A8 was my favorite choice from germany and I have only heard good from my friend who has driven his 2004 A8 over 4 years. But when I tried his Audi couple weeks ago I wasn't satisfied. It sure is nice fast car and looks still fresh but it didn't feel like top of the line to me. It felt like stretched A4 with some extra gadgets. It was kinda too sporty even suspension on comfort setting and definitely too loud. Quattro was really nice I have to admit that.
I'm going to test drive this week Lexus LS430 and I hope it proves to be as smooth, quite and luxurious as I have imagined it to be. I'll let you know how this end up, will I join LS owners or will I put more miles to my Volvo which is nice daily driver.