Thing is, That clearly states that its a "Clone" of the N900 and not an official product.

It would be good if someone could create a guide on how to tell a genuine N900 from a fake one, or at least if any people scammed could provide us with information on where they acquired the product.

OP, Sorry you've had this trouble I'd be pissed.....
As other people have said contact Nokia directly and hopefully they should provide you with documents proving it is fake for PayPal. Luckily PayPal fully protects your purchases so you should get your money back, happy days! Could you provide us with the location you acquired this phone so we can Flag it for potential N900 buyers in the future.

My tip for anyone buying an N900 online, Do it through an official website and try to avoid Ebay unless the user has an AUTHENTIC Pictures and a decent seller rating