Well this Product cost arround 800-1000$ in the USA. But the problem is some people in Lebanon, for example this guy:
http://www.elmazad.com/item/kingston-flash-memory-usb-256gb-christmas-off/59793
is selling each for 75$. They seem to me REAL but infact they aren't They are Counterfeit.
Other people are selling it too for this low price.
Those counterfeit 256gb flash memory, will stop when transferring data, corrupts data, problems in transfers, may be less than 256gb ..... oh and It cannot be formatted to NTFS ( FAT will take year to transfer, slow rate ).
The result, if you use it on the recent computers it will start working and then stop in the middle.
Anyway just so you can make sure it's the real one, you should check if there's a serial number on the flash memory or try formatting it to NTFS, if it get's a BAD SECTOR error then it's fake.
I was going to buy it today, but then i did some searching and found out this.