Dan's chaps are the best I have found. They run around $30 and will last, I buy all my briar proof stuff from Dan's and absolutely love it. I believe they do make two different thickness and you want the heavier one.
Here are two sites you can order from:
http://splitoakkennelsupply.com:80/Site/Home-1.htmlhttp://www.windwalkeroutdoors.com/Scripts/default.asp