Actually they were $12 at some point ... I should've ordered more of them at that time. I've been using them for testing various quantities of NanoFury boards and so far they've been performing pretty well.
A follow-up :
I've been using those Amazon ones for testing of the dual-chip design and I am very impressed by them - I've plugged them into USB3 ports and 3 miners are happily hashing there when pushed to the limit.
And a very disappointing observations from this one:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817111981 (and there are a lot of similar ones with 2.5A power brick)
The power brick is a piece of junk and as soon as you add some load to the hub (let's say 1-1.5A) the voltage drops to 4.6-4.7V and if you push it even harder it goes even below 4V.
This was a nasty surprise for my desktop which in essence ended up having to provide all the power as that power brick's voltage was well below the PC's 5V.