Pricing & Taxes: iPhone 4 Factory Unlocked from CA, HK, SG

[crashnburn]

Pricing & Taxes: iPhone 4 Factory Unlocked from CA, HK, SG

I am looking at buying the iPhone 4 factory unlocked from one of these 3 places. (Cheapest factory unlocked and without contract).

The thing is the Apple store shows Tax only on one of the Shopping Carts. I am wondering if that will be the case during checkout or will relevant TAX become applicable.

Also, is there Tax exemption / rebate / refund any of these places like in Europe where some places you can claim tax back at the airport etc since you are shopping it and leaving the country (i.e. as a tourist).

Apple Stores with 32GB iPhone 4 (Instore prices and in cart price.. not yet in checkout phase (requires signing up on the site)):

HK - 5888
In cart - 5888 HKD = 758 USD

CA - 779
In cart - 779 CAD = 761 USD

SG - 979.44
In cart - 979.44 + 68.56 GST = 1048 SGD = 773 USD

I am guessing Singapore adds taxes since its only location has a certain GST.

How does / would the Sales Tax / Taxes added on the HK & CA sites change when signed on / when checking out / ... depending on where item gets delivered?