Basically there are a load of shop on ebay that sell custom made costumes, you will have to be prepared to import though.
So far i've only ever bought one thing, which was a dress from TSSY2005. It came quicker than i thought it would and it fit well. Looking through those shop again though i have to say i really am tempted to another outfit...maybe something Bleach
I always make my costumes and I will recommend making it, but since you say that we shouldn't suggest making it to you then you can try this seller from Ebay to make it for you ~ http://stores.ebay.com/honestdragonchin ... tions.html
Since I always make my costumes, I haven't used that seller before, but my friend who uses that seller ocassionally says that she provides good service and she is good at costume making.
Cosplay Magic is also another site that makes costumes for you, but I never brought anything from that site so i don;t know how they are like.