Absolutely 100% REAL. Remember that estate auction a few weeks ago with a few other rares? (frankenstein's monster, Quintana Roo, Jawbreaker). This is the same one... I'm the owner and have all the documentation from Tempe Estate Auctions if anyone needs it. I Couldn't resist the great price I got it for. I have sold a few other Xante's for several times over (privately) what I paid for this one...and this is one of the nicer ones I've owned.
I also sold the Mr. Boston Clean Sweep for a (possibly record price) not too long ago (cart only).
Here's the old thread for the xante (this exact one). Have all the docs from the estate auction and paypal info so there is no question.
http://atariage.com/forums/topic/255331-2600-xante-worm-war-1-ended/
100 percent authentic and If you have any questions, please contact me on ebay as I RARELY check here. Great R10 cart and one that can't be missed for sure! Thank you.