aspekt wrote in Two very different questions based on your personal experien:First, I was wondering what redflags you watch for when purchasing online, primarily ebay, in relation mostly to counterfeit copies of original material.
Second, I am not really asking for your own private resources, but where would one begin to find estate sales that have TSR items in them? I can google estate sales, but I was wondering how to narrow my query down somewhat.
#2
I have attended estate sales around the Chicagoland area on and off, due to a friend of mine that runs them. It's quite rare to see any D&D items in one actually.
I drove to an auction in Wisconsin a few weeks ago. The auctioneer was telling the story of someone's house cleaning, and they wanted a bunch of stuff thrown out (including a D&D 6th printing white box, and other lesser D&D goodies). The white box sold for $220, plus buyer's premium (oh hell no it wasn't me...).
Craigslist is also hit-and-miss as to if any D&D items come up for sale.
You just have to be persistent and keep looking!!!

RPG’s, D&D in particular has had a major influence in my life. It’s bonded me together with life long friends...it’s that bond in life not just as friends, but in our jokes, our mannerisms, and what we find funny. Invincible Overlord