Dan, I think your understanding of what Import vs. USA are confused. There is absolutely no difference between the USA and Import version (they are all made in the same Japanese factory). But for the few dollars you save you give up a the Canon USA warranty. Buying gray used to save you some money, but with the prices I've seen lately on B&H and Adorama there is no reason to buy Gray. In fact the prices on B&H right now are the same.
I assume you live in the US. If yes, then you should certainly buy USA.
When you go to B&H and pull up the 430EX, click on the link for the word IMPORTED. It explains the difference. This is a partial quote from B&H:
What are the differences as far as a customer is concerned?
In most cases the difference between a USA import and a Grey Market, or imported product, is the cost of the item and the terms of the item’s warranty coverage. The products themselves are otherwise identical in every way. Occasionally the manufacturer might change a product name of model number to differentiate between products targeted for US distribution and products targeted for distribution elsewhere.
When they say product name, they mean Rebel XTi vs. Rebel 450D. Same camera, just different label.
P.S. The Adorama prices are the same as well. Stick with USA.