I've always bought harnesses for my 7 lb. dachshund, from a wonderful lady in TN. Her prices are very reasonable and she'll even add a ruffle, if you want. Her smallest size is quite tiny! Here's a link to her site:
http://www.picturetrail.com/sfx/album/view/3635339
She started making them for dachshunds but now makes them for any small breed.