check eBay or special patch sites...i rememember a Geocities site with something like that from another forum
http://www.cacustom.com They are in California but you might want to try them to see if they have any US Soccer patches. They "might" have some from DC United but that stock is extremely limited. As the official outfitters of the San Jose Earthquakes they might have some leftover stuff from the other teams. If you call or email ask for Brian Holmes. Good luck.