Whilst looking for a Thermapen on Amazon I came across some that are only £24 including postage
They are the genuine Thermapen 3's made by ETI, and sold directly by the manufacturer
I have a feeling they are cheap because they are unpopular colours, I bought a blue one but these have now run out. Mine arrived a few days later with a certificate of calibration dated 1st August 2016 (I did buy it a couple of weeks ago).
Here's the links if you are interested
All the other colours are much more expensive (£44 - £60)
Hope that's of some use to some of you.
PS I don't spend all my time on Amazon!