One alternative might be to print your own decals. You'll need an inkjet printer, pictures of the relevant insignia, some sort of image processing software to resize the insignia, and decal paper.
As another of my hobbies is flying model rockets, I get my paper here:
http://www.rocketstore.co.uk/shop/
Click on the "Product Categories" search box and scroll down to "Consumables" (under "Construction"). You can get clear or white decal paper, and they also sell a suitable spray acrylic lacquer (Humbrol Crystal Clear).
Another source of decal paper:
http://www.craftycomputerpaper.co.uk/productlist.asp?catid=14&RootCatID=14