After being disappointed with ATV grip selection I came up with a great idea. I asked myself what else uses grips? BICYCLES! So I went up to my local bike shop and found a nice pair from ODI 2tone black and blue, soft, and the flange is just right. (it doesn't interfere with throttle)
They cost $12 and obviously both grips have the same diameter holes. I can't believe I never thought of this before. Tip: Try using hairspray when installing new grips, works good for me.

Look in the BMX section of the store.