That doesn't surprise me, as the foreign-owned toy companies make a lot of money from their official outlets in other countries. More money per unit is siphoned back to the head office, than the money they make per unit in their own country.
In the graph I put together using one class of Transformers as an example, it showed that US Hasbro makes about $3 per Deluxe profit when sold in America, while they make about $11 per Deluxe profit (split between US & AUS Hasbro) when sold here.
If more people keep importing Lego/Hasbro/Mattel toys instead of buying from domestic retailers here, those foreign owned companies only get the smaller profit-margin of wherever you imported it from.
(and use other negligible factors as the "official" excuse for the price difference)

Hope this doesn't end up being a trend for Lego, Hasbro & Mattel, to force American online stores from exporting their cheaper products, as BBTS isn't the only site toy-collectors like to use. It was just the most convenient source, to buy a wide range of stuff to save shipping.
This will impact on importing, but wont stop it, as those shipping-forwarding companies will end up doing more business from this.