i was just going to say those two too ... shana's store tinkerbellscloset.com has GREAT stuff and she's really helpful with your order.
other places would be purecanine.com that's run by coley. they have cute htings too and shippings fast.
another place would be des, her store is go.fetch. (i think the website is go.fetch.comcast.net) she has cute things too! lots of stuff. she just got new polos that i'm totally gonna order.
another store is fufu fashions. she has lots of t-shirts too. fufufashions.com is hers.
my other FAVORITE store would have to be chloebella.com but she doesn't have t-shirts but lots of great casual harness vest if you're looking for those.