Wheat is probably the least problematic alternative to corn. In fact, my chickens generally get slightly more wheat (sprouted) than corn.
When you say "wheat berries", that makes me wonder if you're buying them at a health food store or grocery. If that's the case, look for a local feed store and buy a 50# bag. It's more expensive than corn, but not ruinously so. (in my area, and in my opinion)
How many chickens are you feeding?
My mom makes bread from the wheat berries and she buys them from a health food co-op. I assumed since we are eating it, the chickens could eat it! I am going to be feeding ten chickens. It's $28 for a 50# bag.