from my view its authentic
Really? The auction clearly states that it's a clone!
The Arduino is relatively expensive for what it is, and because the design is open it's trivially easy for anyone to clone and sell it cheaply. The name is trademarked, so clones are supposed to be given different names (see the Arduino FAQ).
Some people have reported quality issues with clones (though there were also some with the official boards), so don't expect or ask for support from the official supplier if you find any production defects. You may feel better about supporting the 'real thing' since the money will theoretically go toward developing new products, but that's a personal choice.
Anyway, they're fundamentally pretty simple so not a lot can go wrong, and it seems like a good price for the package.