Hi Mark,
I'm using a JRT-29 Bluetooth GPS which I got off eBay for 23 quid inc postage. The seller had plenty for sale. It is probaly a generic type of unit. This is the same type of unit, but not the same seller.
http://cgi.ebay.co.uk/Bluetooth-42-Channel-GPS-receiver-device-PDA-Car-Lab_W0QQitemZ160162849424QQihZ006QQcategoryZ4668QQssPageNameZWDVWQQrdZ1QQcmdZViewItem.
The seller of mine was based in Hong Kong and the unit took about 5 days from order to delivery. I seem to get around a 4m-5m accuracy on this and was very surprised when I went for a walk yesterday and then downloaded the .kml file into google earth. It seems to get a GPS signal very quickly too, even from a cold start. A bonus is that it uses the same type of charger as the phone, a mini USB plug, so this means only one charger in the car.
On the Phone/PDA I use the Franson GPS Gate as this enables me to use both TomTom and GPSMap go simulataneously. I had to make sure the settings in the phone didn't turn the unit off when on battery power. I have it set to just turn the screen off and leave the unit running. The Bluetooth paired up easily with the GPS and even when turning on the GPS after a few days it finds the phone and they connect flawlessly. I have just bought and external waterproof antenna so I can put the GPS unit in my rucksack and not have worries about it getting wet bit still get a signal.
I don't know about more money than sense, 'cos I'm thinking of getting a standalone PDA for off road navigation purposes. I'm looking at a Dell Axim x51v - seems to have a real good sized screen, but I'm not really clued up on PDA's tho
I'm off walking tomorrow - probably Lakes, but may go to Yorkshire Dales and will test the unit in anger, so to speak.
I'll keep you informed.
Cheers,
Mike.