Fake pens on ebay? Oh man!
Fake Parkers? Nooo!!!!
Fake Parker Sonnets? That's just outrageous!!!!
Buying this particular pen on ebay, and from someone in China, you'd need nothing short of a miracle for it not to be counterfeit.
I purchased a "Perfect Parker IM with 0.5mm nib" once, out of curiosity. The quality was OK, but like the Sonnet (real or counterfeit) its cap's not airtight, so it dries out. The nib, though, is quite good.
I also purchased a lot of 4 Sonnets from someone in the US at a very low price to see if I could figure out a way to deal with that model's drying issue. I've compared them to two Sonnets that I purchased from reputable retailers in person, and if they're fakes, they're crazy good, because I couldn't find any sign of them not being legit. (Before you ask, I never got around to trying something to make the caps airtight... too many projects, too little time.)
best read of the year so far!