Little Sister and Big Daddy photographs via these sites. The watermark indicates they're from Dim Horizon Studios, but I couldn't find anything Bioshock-related there. DHS does have various other prints for sale, however.
UPDATE: Jacob says the costume is by Harrison Krix.
UPDATE 2: They'll be posted at Dim Horizon Studios soon.
UPDATE 3: Harrison Krix posted more photos.
*Previously: Bioshock 2 Special Edition available for preorder.
*Buy Bioshock toys at eBay.