ToysRUs were bad for having prices that were about double the price in Asia and Japan, making it significantly cheaper to import than buying from there... but Zing/EB have been really good for their Transformers exclusives (even their prices for their short-lived stocking of Titans Return toys were equal or less than regular retail).
Zing/EB may be expensive for most of their licensed merchandise, but their recent Transformers items that they've been offering (from Hasbro Asia through Hasbro Australia) have been close to the retail prices in Japan and Asia, and therefore cheaper for most of us because of the pick-up in store option (no international shipping).
Their last five items that are coming from Asia...
MP-19+ Smokescreen - about AU$135 in Japan - AU$130 at Zing/EB
Optimus/Convoy set - about AU$160 in Japan - AU$160 at Zing/EB
MP-13 Soundwave reissue - about AU$220 in Japan - AU$220 at Zing/EB
MPM-8 Megatron - about AU$235 in Japan (it could be slightly different) - about AU$260 in Asia - AU$200 at Zing/EB
Ectotron - about AU$65 in America - about AU$90 in Asia - AU$80 at Zing/EB
TRU (and Myer) was never that good, compared to the retail prices in Asia and Japan.
If the online stores in HK and Singapore have so far been able to offer Unicron for a price that is similar to the US price, it means that Hasbro Asia are selling it to them cheap enough for them to sell at the Hasbro Pulse price and still make a minimum amount of money to cover their costs and profit. Obviously that cheaper price from Hasbro Asia to Asian online stores, than the Hasbro America price to their customers, must be due to the absence of shipping across the pacific, and that postage within America is a lot more expensive.
So I honestly don't see why we can't have Unicron offered here at Zing/EB for a similar price as Asian online stores, just as most of their other Asian Transformers exclusives.