I've never bought one of them myself but I have the same attitude about all the cheap shit on eBay nowadays. If its got the same internals and made out of the same material and clames to so the same thing. It usually does. I've got ph and tds meters from china for about 8 bucks each and they work as well as a Hanna meter and look exactly the same.
Id go for it and read up on the seller history and shit first.