We pulled this "International Price Disclaimer" off a major US retailer's website. The fine print isn't that fine at all.
In addition to the US Dollar exchange rate, you will be subject to hidden fees like brokerage and (possibly) duty.
The real kicker is the refund that happens, should a return be necessary. The only one saving $$ on your purchase is the Credit Card Merchant.
At least this vendor was honest enough to post the warning. Most are not. Beware!