This is a site I stumbled across a while ago, and just now thought about sharing it. I was looking into buying a new gi, and this really was a valuable source of information.
If there is a gi that you're interested in that isn't on there already, you can email the guy that runs the site and either ask to add your review of a gi or see if he has any information he can share with you.
I've contacted him a few times, and he has always been helpful and prompt.
http://www.jokerjitsu.com/gi/