I see you've discovered what I lovingly refer to as the "European Discount" (a little VAT back never hurt nobody, well until you're 10 pipes deep in My Shopping Cart). I've gotten stuff from them before and from others through whatever Express Mail option and didn't have a problem.
I mean this'll vary a bit from state to state but here in NY I don't think the lazy bastards give a damn until it's ~$1000 reported value. I've also found that the Swiss/Germans are usually the only one who might incur a charge and even from there it's rare.