Yeah I know...its dirt cheap! in fact I just bought it yesterday
The 1/2 one I have was of a similar make and similar pricing and it worked fine...up till now.
It's not worth spending too much money on something you might end up changing just after a season!

I also got my self a replacement QEV. The one I have installed is a 1/2 but quite bulky and heavy (I think its brass or steel) Found this on ebay, its smaller and lighter and still 1/2 - might need to modify the outlet though as it looks like its 3/8
http://www.ebay.co.uk/itm/160930294213