I don't think it's worth stressing that much over a few mah rating one way or the other. Just go up on Amazon and buy a good protected cell. I just search for Panasonic 18650 protected, or NCR18650B and read reviews. Decent cells are going to be $6 each or so. Avoid anything that claims to be > 3500 mah, they're guaranteed to be crap.

I think any battery you buy (assuming you get decent name brand ones) is going to be the same within +/- 5% and it's just not worth stressing over.