I have been trying to find a nice thick one myself, and they arent readily available as far as I can tell. I have ordered a couple and so far my favorite (by alot) is the sherlock pipe by penn valley pipe works at pipeshoppe.com
That one is the definite winner by alot
thesmokindragon had a pic on another post but it didn't give the manufacturer it looked nice. kinda hope he hits this post and lets us know.
Try this site; you will not regret: Penn Valley Pipes and Tobacco Co.
The owner grants excellent customer service.
You can try pamplin clay bowl with reed stem. I have not tried it yet, but my package is on the way.
You can also try Dawnmist Studio The pipe-maker will be making new pipes in mid-Feb, so you would have some time to choose which one you would like to order.
But, is clay pipe with thick wall somehow better than other ones? I think they are just all the same...