There's this one from RS....
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And there's this on ebay....
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Possibly the cheapie is a fake but it's a very good one if it is (I've got one).
Same goes for tips on ebay. Branded 900M tips can be had for around $1.50 (including postage) whereas local suppliers charge $13 or so (RS want $22) and they're indistinguishable (I've got both)... not to be confused with what are very obviously non genuine tips.