I picked one up last year, its been great!
I paid 20k with 110km and it was an american import. (Previous owner imported it) In the States they are becoming a little harder to find in good shape as more and more people are buying them for the Offroad premise. Same basics as a V8 4runner, but with a way nicer interior and more likey driven by a soccer Mom. All of the suspension bits transfer over from a 4runner, Tacoma and early model FJ.
Timing belt needs to be replaced at 160km, got a qute locally and it was around $1200, not a huge deal.
Rear airbags can start to leak, but its a few hundred dollars to convert to regular coils, but super easy as I did mine a few weeks ago. OEM shocks are pricey to replace, but again many people go aftermarket.
It seems like the non navigation ones are most sought after, as you can replace with an aftermarket deck for all the modern amenities. I have oem Nav with a VAIS tech plug in for USB/ipod connectivity, and Ive been very happy with it. Sport package is also great to get, but like a needle in a haystack. They have a tinted look headlights and fogs with black interior as well as some suspension differences.
This page shows the main differences:
http://www.toyota120.com/html/lexus_gx470.html
If you have any questions, feel free to ask!
For me, I went with a 2007 for the vvti engine and the aux port up front..also more up to date Nav.