If you buy from Farnell, or RS, or Amazon, or eBuyer, or PC World, or Dixons, then you can be fairly sure that what you are buying is safe and appropriate. And if it isn't then you can report them to the Office of Fair Trading, Watchdog, Which and the Small Claims Court.
If you buy from eBay, you get it cheap.
Caveat Emptor and TANSTAAFL.
But eBuyer and Amazon both sell this hub. How are we supposed to know what's good and what's crap? I ordered one from eBay for £3.49 then finished reading the thread - I just informed the seller that I am cancelling under the Distance Selling Regulations.
This is a bit of a problem - can't go round Maplin or Currys with a meter demanding to test all the power supplies...
But RussIT said,
I have this exact same hub but with a 3A PSU, I just measured the voltage with my htc phone and a 2.5 inch hard disk attached and the voltage is about 5.2V at the USB connector on the hub.
I would trust the one from eBuyer, and I would trust the one from Amazon, if it is being sold by Amazon and not a Marketplace seller. It sounds as if at least some sellers are selling it with a decent power supply. Whether those units also have the five-volt feedback problem I don't know and I would worry about that. But it wont break anything even if it does cause problems. It will just put that USB port out of action for an hour. On the other hand it is not good practise to have two power supplies fighting over supplying power. You could have over an Amp flowing because one is supplying 4.75V and the other 5.25V.
You've got two decent choices here. Either buy this one from eBuyer (who will understand you when you complain) and test it when you receive it, or buy a big name device from a big name distributor with the expectation that they wont ship rubbish and if they do they will support you.
You probably don't want to buy a different no-name device, since you don't know what problems that one might have.