What kind of dun is it? I think it's a pretty forgiving colour, most things look nice on a dun. If she's only 7 then I suppose it doesn't matter if she grows out of pink in a couple of years as she will probably need new ones anyway
Couldn't get pink things when I had my pony, green was exotic compared to everyone else's red or navy, but that was 20 years ago now
i used these people, and i got saddle cloth, long rugby type shirt, and hat cover. i must say that the quality is good and the delivery is quick too http://www.custom-xc.com/
I went for light blue and dark blue stripey rugby shirt and matchy hat silk on my Dun, got both from Robinson's. Dun is a great colour and I don't think any colour would not suit it, I think a stripey purple and pink rugby shirt with matchy hat silk will look lovely