Trust me, you can spot a counterfeit a mile away.
There are no 'real looking real functioning' CFit iphones.
There's crappy copies, they feel like junk and say stuff like iPhone Air or iPhone Mini or M8. They use Fake OSes which are slow and don't really work. They are dumb phones plain and simple, they cost sand feel like $80
An unlocked HK 3gs will cost $700 ish USD for a 16GB. (this price is here in Beijing, in HK it might be $15-$30 cheaper).
I could probably get a good deal if I bought in bulk but I don't know how many people want Factory Unlocked 3GS' in america.
IIRC, a guy had them for $615 here in Beijing, I don't really remember it's been awhile since I checked the prices.
However I don't know about them in the airport, there are a lot of foreigners there, which means it'll cost $1,000... If you can find it.
I just checked, it's cheaper on ebay.