I am in thailand right now and went for a walk through the MBK centre in Bangkok.
on the 4th floor there is a whole floor full of mobile phone shops and it is full of iphone 4 handsets.
There is no shortage at all in bangkok, every store I go into has them in bangkok.
Prices are about the same once you convert thai baht to NZ Dollars but you can bargin and get them down a little bit.