If they're coming from China, my experience has generally been about 1.5 weeks. China Post stuff sometimes takes 2 weeks. DealExtreme takes 3 but I'm convinced that's because they're lying when they say they shipped something.

Yes, I don't think you can possibly do better than buying spare phone batteries. No other battery will be as compact for the amount of power delivered, extra phone batteries are cheap, and you don't have to carry some additional means to charge batteries.