Can it be run without the grip ? I'm assuming it's like the add-on grip I had for my 5D . Any chance of converting it to use AA's with parts from a non gripped donor?One guy is selling battery grip, charger and battery for $345, only one. I checked photo dealers, ebay, craig's list. Problem is, even if I found a OEM battery, how much life would be left in it? Only supposed to be good for 4-5 years.