Not actually a crock but a few sites that do things that may work.
http://www.cowboycooking.com/barrels.html. This contains a Sour Dough Keg. It may work.
http://www.rptrading.biz/WoodenBuckets.html. This one has wooden buckets that hold water.
There are a couple of other sites that do barrels specifically one of which is
http://www.kentuckybarrels.com/.
I'm guessing if you have a specific picture or you can describe the crock one of the sites could build it. Hope this helps.