I started a discussion on the sculptor's forum about your dragon, thought you might be interested.
http://www.frothersunite.co.uk/phpBB2/viewtopic.php?t=14949&postdays=0&postorder=asc&start=0&sid=5d2d5df908d513c48a33a509048e5e42
Be warned that honest opinions are aired on the sculptors forum, you won't get a continuous stream of praise - but you will get honest feedback. Generally, I think it's well recieved - some discussion about the belly scales.
Regards casting, you need to cut him up - like remove the legs probably neck and tail etc - wings obviously - he'd be in several parts in the end I'd imagine, but the flat areas like where the tail is removed gives a place to pour the resin into the mould. (I don't do any resin myself - and this will be too large for metal casting I think)
For descent quality resin (without bubbles) you want someone that has a vacuum cylinder - you can ask that.
Regards cost, my advice would be to seek out someone would mould and cast it for you (you could ask that question on the sculpting forum) and get a rough estimate for the cost of producing the moulds - and casting up say 10 dragons. Once you have an idea what that might cost you can decide on a price per dragon .. so 10 dragons might bring you £xxx. Once you know the numbers and decided if you want to give it a whirl - I'd suggest you ask people to pre-order with you - ie. send you the money in advance - you could offer people free post if they order in advance or something as an incentive. If you sell 10, you'll have the cash to get 10 made, no risk. If you don't sell any, or you only sell 2 say, you'll know it's a bad idea, and you can appologies and refund the people that sent you money.
Personally, I think it's a very nice looking dragon, could have more than one head option if you sculpt some alternatives - you could do wings spread or wings closed as more options.. it would be nice if it fitted on the same size base as the current GW dragon model - so it can be used within the rules of the game.
[/url]