Hello, I got a 2007 IS 250 SE MM in Aug last year and I would add:
1: Check the alloy wheel condition. Mine was still in warranty and I had them all replaced. Perhaps push for replacements if they are blistered or kerb scrubbed.
2: Get some mud flaps fitted with the deal.
3: Test drive for as long as you can over variety of roads that you know.
4: Check tyre depth.
5: Check the front discs for wear if you can.
6: Do a thorough body panel check for alignment, especially bumpers and check bumpers for slight paint cracks...sign of being dinked.
7: Check all paper work and make sure all services are/have been done recently.
8: Get the last owners name from the V5 and if you can call them up and ask them about the car and it's history.
9: Push and push as per the Lexus brochures that the car should be as good as new condition.
I love mine and wish I had bought one years ago.
Hope the deal goes well.