Best place to purchase an UNLOCKED handset ?

exel1966

Removed !!!

grumbler

I think that a place that is the best for all sim-free phones doesn't exist.
You can start with CPW and daughter companies (e2save, osps, mobiles.co.uk). Not only they sell sim-free phones, but all PAYG and contract phones they sell are usually unlocked. Don't forget about quidco/TCB.

Also, many handsets, e.g. very popular android Orange San Francisco from Orange, can be easily unlocked for free. Many can be unlocked for a small charge.

T_T_2

As Grumbler says, you might be coming at this from the wrong angle. Rather than limit your search to companies offering unlocked handsets it might prove to be more economical to come up with a selection of handsets that your friend would be happy to own, see who sells them cheapest and figure out how much it will cost to get them unlocked. The price varies from free up to £15.00 in the vast majority of cases. Be sure to do your research as there are numerous methods involved in unlocking phones and some approaches run the risk of corrupting your IMEI number which will prevent the handset from declaring itself to networks correctly.