I got them on Amazon:
Flag Decals. Definately not an easy install! The first set I messed up, but they kindly sent me another set for free. I chose the "wet" install. After getting them positioned right, I used a heat gun to warm the vinyl and help drying BEFORE removing the backing paper. Using the wet method is more forgiving when trying to position the decal. Once you get it perfect, squeegee it pretty good to get the liquid out from under the vinyl and then lightly hit it with the heat. Wait at least 20-30 minutes before removing the backing paper. Slow and steady, peel the paper straight back, not up, using the squeegee to work out any bubbles as you go.