Now, if you're buying it for its 'collectability' shouldn't you feel some responsibility in vetting the vendor's credentials and/or enter in to terms by which you can return the item if you determine its fake?
Well, here's my experience as a non-collector with fraudulent merchandise.
Order DVD set. Price is actually pretty steep but less than some other sellers. Seller guarantees it's "not counterfeit" on their page, of course.
DVD set arrives. Nice box, good silkscreening.
Play first DVD. First episode subtitle translations are obviously bad fansubs (I've seen the same on online downloads). Second episode actually has scan lines where it was copied from analogue->digital
Report counterfeit merchandise to eBay.
Ebay says I must get the item certified as a counterfeit by an industry professional, despite the obvious signs, and within a fairly short time frame. As I was living in a shithole town at the time, this was a no-go, so I was out about $60-80 for a cheap piece of garbage which I could just as well have downloaded online.
So even if you're knowledgeable enough to vet something as authentic or otherwise, eBay pretty much makes it as hard as possible to get a return on counterfeit goods (or at least they did last time I dealt with them).
Same deal with fake USB/SD storage devices. Tons of counterfeit, and eBay seems to not give a flying f*** about it.