It might be expensive but you can try requesting a custom order from a seller on Etsy. Look around the site to see who makes clothes for plushes and dolls. Ask them if they are willing to do this custom order for you and for what price. Make sure to find out if you need to acquire the plush first or if they can do it for you but charge more. Ask questions. Don't be left with just the outfit.
There are a lot of U.S. sellers on Etsy. Most of the sellers that I purchased from were within the U.S. If you need the item by a certain timeframe, you have to let the seller know beforehand. If the seller can't handle the deadline, they just refuse the order request.
Yeah, international shipping can be very long sometimes (30+ days). I have gotten things that arrived within 2 weeks as well though so it does depend.
If you like things to arrive quickly and don't mind paying a bit more, you can filter your search results to narrow it down to only those in the United States.