Hmmm...
I am guessing I am the only person here on CMoN that is also an active member of the Citadel Collecting community...
To answer the original question, yes that figure is an \"unreleased\" figure in that it has never been officially released. It can be seen on the Stuff of Legends site under Citadel Rarities:
http://solegends.com/citrare/index.htm
(it\'s the top of the fantasy list on the left side).
Now, that said, for an \"unreleased\" figure, I see it on eBay VERY frequently. So frequently that either a number of them got released somehow or it has been recast a lot (likely both). I would never buy one from eBay without personally knowing the seller, and knowing they got it directly from someone inside GW since I would otherwise doubt the authenticity of it. There are just too many of them offered up for sale to make me trust them. It\'s like buying Centurius out of the blister - it\'s probably a fake.
But unreleased figures, even bad ones if they are from popular lines such as Marines, can sell for a lot of money, even hundreds of dollars.
And that Imperial Dragon you mentioned has been escalating a lot in value over the last few years. $700 would be considered a bargain now. $1500 is commonly accepted as the base price for them these days, though the last one to hit eBay that I know of was the subject of some deep pocketed bidding wars and finished at over $5000!