Why Is This Shield Nickel So Expensive?

This pretty well sums it up. One or two people got caught up in the bidding with doing the proper research. It's a sellers' dream and a buyer's nightmare.

is it a variety of any sort with the obverse die crack? As common as die cracks on classic nickels are, and they make some of them quite unique coins, is this driving the bidding?

Its either that or I think that the experienced bidder realized the low feedback bidder was a shill and played the game and would have returned it even if they won its just that the shill took one too may shots and got stuck with it. I don't read this is a case of buyers ignorance.

Two things jump out at me:

1. Shattered die obverse with field displacement at upper left. That in and of itself is collectible, even on a series known for spectacular die failures.
2. The coin appears to be at least one grade higher than a MS63. Look at the surfaces -- hardly any bag marks, little handling rub if any, a full strike despite the die issues...

It's worth a premium over a 63 -- but I would have put its max value around $250-$275, not $700!

This may be a case of "buyer rage" -- a buyer realizes they're not going to win a coin they want, so they repeatedly drive up the bid out of spite just to prevent the other buyer from obtaining the coin, and then pull a bid cancellation or "i don't want it" or something similar, and both the seller and the other buyer are hosed. The buyer who won is low FB (sub 100); the other buyer is 2k+ and has bought other coins from seller, but it does not look like a shill.