Just found that Discover offers 10% cashback for purchase on Panasonic US website. I just ordered Pany 12-35 f2.8, the promotion price is $899 ending tomorrow. Considering the 10% back, the final price around $810 becomes the lowest one I found, even cheaper than Japan imports on ebay. You can do the same thing for GH4 ($1500 now). It will be even better if you are in a no-tax state.