Detecting Arduino Clones?

Been looking at buying another Arduino and looking on eBay and I see there are a ton of clones which i have filtered out. I've got a few listing where the sellers claims its an official board.

How can I determine if it really is official?

I guess I might be answering my own question here - its from a seller in HK and its fairly cheap?

Is there a way to determine it its a clone or not? If it is should i report him for trying to sell off a official part?

The only way to guarantee it is not a clone is to buy it from an official distributor:

For example, there is only one distributor listed in HK:
Hong Kong: Self Built

Thanks - I'll do that.

Is there a way to determine it its a clone or not?

A "clone" is in-bounds as long as the board does not display the Arduino logo or the vendor does not claim the board to be authentic. For example, calling a board "Arduino compatible" is in-bounds.

GregM:
If it is should i report him for trying to sell off a official part?

If the board or the advertisement shows the Arduino logo or the vendor claims the board to be authentic and you believe it is not genuine then you should.