What price range are they running? There are plenty of legitimate Titleist bags on ebay. I bought mine off ebay (2014 model ultra lightweight stand bag). I'd be a little suspicious unless it's an auction style listing.

Counterfeiting has become a major issue in the golf industry.  I've become very leery of buying anything off ebay unless it's a "reputable" company.  If you see styles or colors not in the catalog it could be an older style or even from a different market.  But at the same time, it could be fake.  I would say, buyer beware.  Do your homework and check out the seller.

Its's not worth what you think your're going to save on ebay. Find a Titleist Retailer and make your purchase from them..