As you know, most of the prices new are nearly £200, although you can get one a bit cheaper from the US.
I have just picked one up from a scrapyard for £15 + VAT - looks in good condition and works a treat.
£9 for a Draper tool (Volvo one is probably better, but Jeffrey could not find it).
£28 for the whole job, so very pleased.
You could try your local scrapyard or Aldershot Car Spares 0n 01252 721969 (
www.aldershotcarspares.com). I had to wait around for half an hour while someone went to unscrew one. I don't think that they are particularly knowledgeable about the costs of some of the sensors and I suspect that £15 is the standard charge. If you do try them, specify the front sensor and of course the Denso number.
Graham