I just recently bought a harness, which I personally believe to be the most effective and most comfortable harness for small dogs.
The company name is Puppia. It was $20. As a general matter, I think Puppia has the most cost efficient + the most aesthetically pleasing + effective accessories and clothes that you can buy for a dog.
Here is their website, which you can't order off of, but can browse:
http://www.epup.co.kr/puppia2/english/index.htm
Here is the harness: