I cheaped out by using 1 ½ inch pine for stall walls instead of tongue and groove. Its stout and looks just fine to me.

Now that I'm done, I'm insured (that's too much work just in case it burns down!) and satisfied. I'm considering some protective edging to keep cribbers from chewing up my hard work. And I'm deciding about pouring cement down the center aisle. I also don't have electricity other than a super long heavy gage extension cord and water other than my garden hose.