hello, was looking at getting this mod and wanted to know cheap batteries i could use for it. I was looking at Ultra Fire 4.2V Li-ion 6000mAh. Do they have to be a flat top? or can they have a top point like a AA? Also i found the cloupor gt 80w for $42 free shipping any better deals? im gonna use the mod wth my ijust 2 tank with 0.15 ni200 coils