You might want to check out the Disboutique group here:
http://www.disboards.com/showthread.php?t=2462031&page=105
They make custom clothing for their kids....a few of them sell their customs on ebay and etsy. Because Disboards won't allow them to advertise their customs you'll have to make inquiry and have them contact you privately off board if any of them are able/willing to make the design you requested.
For a capable seamstress this is complex, but not extremely difficult. The bodice and skirt are similiar to many commerically available patterns. The neckline would be the most creative part of it, but there are many commercially available patterns with similiar victorian necklines, so if you can combine patterns to make one outfit it's definitely do-able. If non of the disboutiquers can help you, contact fabric stores in your area and ask for a referral to a local seamstress.