Motorola BP6X battery
I recently purchased what is presumably a Genuine Motorola BP6X battery from a reputable 3rd party vendor for dirt cheap ($5). The BP6X is the standard battery for all Moto Droid 1's and 2's. Everything seems to be cosmetically fine but I noticed that the date of manufacture is 8/14/2009, which is probably one of the reasons why it is so inexpensive. For comparison, the battery that came with my Droid 2 Global appears to be manufactured on 10/8/2010.
Motorola P323 battery charger
This is the standalone OEM battery charger which is able to charge a handful of different Motorola battery models. You can power it by either micro or mini USB cable. The two biggest advantages I can think of for this battery charger is the fact that you're most likely going to be powering it from your stock Moto power supply, which is a reliable power source. Also, you can charge your battery in the car.
Ebay batteries & chargers
The reason I'm stressing using OEM pieces is because of my unpleasant experience with generic aftermarket parts from Hong Kong. The $1 standalone battery wall charger fell apart pretty easily.
The dirt cheap generic batteries I got held a good charge, but the indicator was extremely inaccurate. The battery life indicator would drain extremely fast and be in the red for 5 hours on my Droid 1. My Droid 2 Global just shows what I think was a "?" in battery indicator.
Last but not least, since the batteries are not manufactured to Moto's specs, these generic batteries did not fit properly in the Moto P323 charger. The contact points did not line up perfectly, so I had to prop the battery up at an angle to get it to charge. On the other hand, my new Moto BP6X battery I got from the 3rd-party Amazon seller fit perfectly fine.