Here is an interesting company that I found through my friend Eric who has been designing decals for model cars:
http://www.ffsmc-productions.com/en/24-118-scale?p=2
FFSMC provide many decals for 1:18 model cars with a great selection for RS200 1:18 models (most designed by Eric I believe). I deal if you want to convert an RS200 model to a version that is not (yet ?) available out there.