We've got a nice one that our club more or less shares being as the puppies grow out of them so quickly. There is a small mom & pop shop here in Houston that makes the harnesses and they are very nice quality. I can take a picture of the one we have at training tomorrow and get you the number to the shop if you would like. The harness is very nice quality and not cheapy/flimsy like the Petsmart ones. It is still nylon but heavier duty, reinforced w/ much wider straps.
Check out Can-Am at http://www.dhart.com/canam-k9/harnesse.htm They will make things custom, plus they have a couple of harness that can be purchased in puppy sizes. I have the harness they show on the Bouvier in an adult size, have had it for years (at least 10) and love it. Their leather work is also good, I don't have one of their leather harnesses but I do have a bunch of their agitation collars, my favorite one I think I've had for 12-13 years.