Try another dealer. I use to get run arounds from one dealer and then I go to another and they have it. It just might work. Good luck.
My buddy just told me a Lexus dealer should have touch up paint for your car. He owns a '93 LS400 (pearl white) and he recently purchased touch up paint for that year. I'm not very good at math but I think that car is older than yours. His touch up paint came in 2 containers. Base and the clear with pearl in it.