I limited the poll to items that usually sell for $100+, therefore Deities & Demigods with Cthulhu didn't make the cut since it usually doesn't sell for over $100.  If included, it surely would have won most overrated.  

If I had to rank them in terms of being overrated then #1 would be:
1) 10th Anniversary sets (they're standard items shrinked together with a piece of paper, I don't get it).
2) Dragon #1 (your average D&D fan would go crazy over it, but it just isn't that rare, the Dragon CD-ROM also take some luster off of it)
3) Orange B3 (there's probably a lot more out there than most people think and the interior artwork isn't very risque)
4) PotVQ (TSR distributed it but didn't make it so not a true TSR item to my eyes)
5) Limited Edition tournament modules and woodgrain box (they're certainly rare and cool like Dragon #1 but one can get practically the same content with later editions)
6) Jade Hare without the cover is overrated, but with the cover it seems to be extremely rare.  Jade Hare with the cover I might say is underrated.  
7) ST1 I'd also say is underrated.  There are no later editions and it seems the original edition got mostly mulched.  It's the one item I'd want more than any others.  

Though it didn't fit into the parameters, the Adventurer's Guild modules are overrated.  Once some PDF king gets a hold of them they're going to be all over the place and I don't know how anyone is going to be able to tell the originals from the copies since the originals were printed on modern printers everyone has access to.  
The Fighting Wheel seemed to come down to a modest final bid level recently but then shot up again.   Hmm...

But for my two coppers, ST1 is the most underrated, then again I don't have one, and have most of the others, so that probably colors my view.  

darkseraphim wrote:Jade Hare, hands down.

It has no classic feel, it was produced too late.
It doesn't reprint any classic or excellent material.
There's very little content.
It has no provenance relating to an interesting event (like a con).
It was not the first version of a classic, such as Tsojconth, Inverness, or Tamoachan.
It doesn't even have original artwork; the cover (when it's even there) was derived from the first Endless Quest book.

Great author?  No.
Great time capsule?  No.
Great material?  No.
Great story behind the creation?  No.
First indication of better things to come?  No.
Throwaway product whose prestige is based entirely on numeric rarity?  You betcha.

Whew!  Excellent points all round!  
What's your take on the others?

White box. Hands down the most overrated, expensive item out there. Right now, at least......

It has to be the 10th Anniversary crap.

Anything that says "Collector's Set" or "Collector's Edition" on it...  Isn't.

Deadlord36 wrote:White box. Hands down the most overrated, expensive item out there. Right now, at least......

Darn, I just bought one for $85 with a water stained box.

But it also means that there aere enough people out there that still want one.  Things could be worse and everyone dumps there #1's at the same time.  Then you will really be crying.