i like glamourdog.com but its expensive
and mygofetch.com for pjs
tinkerbellscloset.com she makes really nice dresses. shes a yt member as well
funnyfur.com is a fav of mine
try monkey daze.com they have nice stuff:
http://www.monkeydaze.com/shopping/g..._title=clothes
i think this site has cute casual clothing:
http://www.teacupspuppies.com/teacupdogclothes.htm 
hope you find what youre looking for!