PSP Memory Stick Pro Duo 4gb

For those of you who own PSP here in Singapore, heres the low down one memory stick prices. It appears that many shops who are advertising SanDisk 4GB versions have run out of stock. I managed to buy the last 4 pieces from Alan Photo at level 1 (it's a camera shop) for S$84. No 8GB version found there. The original Sony brand is just too pricy