If the car still has warranty the wheels etc will be covered anyway.
I brought an 07 approved Lexus in March. When I was looking for one they were a bit hard to get hold of, I wanted a Claxton Grey with Black interior, I was doing what you are, checking the websites daily and when I saw the type I wanted I got on the blower and asked them to keep it until my old man had been round to look at it as I was overseas.
Obviously the car was immaculate so I brought it, I know it may be higher in price but I got the peace of mind buying an approved car. There was a couple of issues that had to be done like the squeaky dash which is common and a couple of other minor things; they took it back with no queries whatsoever and repaired it. They even changed the locking wheel nuts as the old ones were rusting slightly, this was done under warranty.
I did not negotiate too much on the price as they gave me a fairly good price for my 57 Astra, Lexus Wolverhampton offered me 950 more than Lexus Birmingham did, how they worked that out I don't know :o
The car is back now from the repairs and I am stuck overseas again and not coming home till the end of May. I can't wait to get back and drive the car.
I cannot praise the team at Lexus Wolverhampton enough, they have been real helpful to me keeping in touch via emails and I will drive there to get the car serviced etc even though Lexus Birmingham is nearer.