This is a very old review, but I have to say that Jim Lee changed my life in 2007 when he drew my Batman convention sketch.
It was Supercon 2007, and only did sketches for the first 5 people in line. I was number 6. He told me if I wanted a sketch to come back later in the day, but I told him I had to go to prom at 5pm and would have to leave around 1pm. Jim told me to come before I left, and he would see what he could do.
I came back at 12:30, and Jim motioned me over and drew my Batman sketch. To this day, it's one of my favorite pieces 1) because it's a Jim Lee and 2) because of the story.
Jim is a great guy and though he has a very high rate, if you can flag him down at a convention you might just get lucky like me.