Well i found this site..not sure if it is something you would be interested in, but the shirts have trim, however, you can pick the trim to be the same color as the shirt! PLus they are $14 each.
http://www.doggieshirts.com/Tshirt.htm
Just a thought but maybe you could contact
http://www.barkindogclothes.com/ and see if they can help you too??? They seem really nice! Good luck hope this helps!