Given the choice, choose Hong Kong. It is the cheapest place on the planet to purchase a PS3 given their very low taxation. The console (if you sent your friend to the Mong Kok district to buy one) will be ~£255.

However, you need to be aware of UK Import Taxes and Duty.

I recommend a Japanese PS3 if the vendor stocks them:

It will provide:

Region A Blue-Ray (Compatible with the USA)

Region 2 DVD (although NTSC only)

Region 2 PS3 Games

NTSC JAPAN PS1 & PS2 support.

Although listed as a 100v 60Hz Power Supply, the machine should take a UK 320v / 50Hz input. Check this my taking the cover off your console and read the notes printed on the actual PSU.