I do not have ANY unique D&D items at all. I do have a few rare items though.
A Shrink-wrapped copy of B3: Palace of the Silver Princess (orange cover).
A Near-Mint Box with mint books of the Second Print Run of the Original
Woodgrain Box Set. (A "Second Woody").
A Pristine copy of a True First Print of Greyhawk.
A copy of each of Dragon magazines first 7 issues, each in Near Mint condition
A second edition of Chainmail by Guidon Games in Near Mint condition.
At least one copy of each of the RPGA and R modules. (No pre-pubs though)
At least one copy of each of the Strategic Review issues 1-7. All in Near Mint condition.
About a dozen White box Sets. All of them are complete, and they range from Mint to Poor conditions.
And other items that are more common.
I have bid many times on more expensive and rare items too, such as
ST1,
POTVQ, Pharaoh, and Rahasia (Daystar West) each time unsuccessfully.
I also recently owned a Near-Mint copy of Chainmail; Guidon Games, 1st Edition. I traded it to another collector a short time ago for other rare items.
I do not have anywhere near 3000 D&D Items. Even counting common items and duplicates, such as B-2, Core Rules Books and White box Sets, I doubt if I have anywhere near 500 individual items..... As such I recon I would be considered an amateur collector.
Possibly I am in the top million or so collectors out there, certainly nowhere near the top 5...
Of course as for
RPG's; I only collect D&D Items from the first and second editions, I collect no other
RPG's at all and I do not (Usually) re-sell. In the three years that I have been visiting E-Bay, I have purchased about 300 different auction listings (About 400 items in all) on E-Bay and I have only had about 8 auction listings (As a seller) on E-Bay. And all of those listings were for extra copies of items that I was unloading.
As an aside, I also collect Older Comic books, Older Pro Football Cards and other football memorabilia, and some Older Antique Scientific (Surveying) Instruments.