Update : The link provided here is for Apple Canada site. US availability is not known yet but starts at $649 instead of the reported $699.
Unlocked iPhone 5 will be available from day 1 of its availability in the US for a whooping $699 for the 16GB variant with a $100 premium for each additional 16GB, no surprises there!
It is available to preorder starting September 14, 2012 with delivery date pegged at September 21st. If I were you, I would buy it online – get some cashback, free shipping and peace of mind!
Buying it unlocked won’t tie you to a carrier which is good! Don’t forget to buy it through Discover cashback or Bank of America. 5% cashback can be a lot given the high sticker price.