Thanks for you help, but I won't buy a Yamato No Paint kit just for the decals, provided I could even find one!
The ones sold on Ebay might come from this kit, but I'm sure there are quality differences between the various sellers, and the ones I bought were really poor quality...If someone here bought from some ebay seller and are happy with the quality, I would really appreciate if you could point me in the right direction.
As for the matte or flat finish, I don't want to use a spray can, I'm using a brush to apply the product only on the decal.