It sounds like you can print your own. Try this link, It'll give you a 3.9" x 2.6" (100mm x 66mm) flag at 300dpi. You could probably enlarge it with a program like Photoshop to 150% without much loss if you wanted.

http://pfutebol.com/images/Team%20Lo...gal%20flag.gif

I find many decals/images on Google - Images; if that's not exactly what you want. And you can tell it what size to look for.