I'm in California and I pay tax on both Amazon and KEH.
EX+ has been hit and miss for me when buying from KEH. I purchased a D2x rated at EX+ and it showed up in the rated condition. A month later I purchased a D200 rated at EX+, I paid for 2 day shipping and they didn't ship until the day it was supposed to arrive at my door step. The D200 was also missing the 10 Pin cap and they removed the factory battery charger and substituted some really cheap (and I mean REALLY cheap) Chinese battery charger.
I would not have paid as much as I did had I not had a better experience when I purchased the D2x.