ok, here is the final math:
B&H price on the USA lens: $449 + $9.90 shipping (3-5 day UPS) = $459
Sigma4Less price on USA lens: $434 + $18.60 shipping (3-5 day UPS) = $453
your saving: a whooping $6!!!!!!
If you're still looking for this lens, don't forget about Amazon: $431.62 with free shipping. I've been checking prices for this lens daily and this is the lowest I've seen except for eBay.
Just noticed that Beach Camera (via Amazon) has it for $424 with free shipping!
[Edit] Guess I wasn't digging deep enough before. Just found this lens on buydig.com for $409 with free shipping and it says brand new with manufacturers USA warranty. think I'm gonna pull the trigger on this one.