I am trying to find a 6 speed manual sedan. All my reserach indicates that these did not come available until 2004, but a Carmax in Richmond, VA says they have a 2003 6 speed manual on their lot. Is this possible?

Yes, there are 2003 6MT's, not very many though.

When I was shopping for my G35 I had my heart set on one. I missed 1 by about 30 mins. and drove a very nice one but the guy wanted $29,000 with 20,000 miles. I even talked to dealers 1000's of miles away but shyed away from the logistics. I finaly settled for a new automatic, it's not bad but I still wish I'd gotten a manual. Hope you find one .