Bluetooth GPS receiver for Nokia 6120.

Can anyone recommend a good reliable one? Quality is more important
than price.

I have a TomTom 920 for the car but I'm looking for one I can use for
walking around (mostly urban). My phone has Nokia Maps and I can buy
TomTom software for it as well.

Preferably one that will keep the signal even when walking around
between tall buildings, and is somehow "wearable" on my person.

Finally, I've looked around a few likely shops (Currys, Comet,
Carphone Warehouse, Halfords) and none of them stock this kind of
device.

I suppose the internet is the best bet?

MTIA