Well, $12 for 850 mAh was Energizer (talk about brand pricing 
), and the $6 one for 1000 mAh was from Polaroid.
EDIT: Just realized, they're actually 850 and 1000, respectively.
I once got a pack of Polaroid for about that price at Wal-Mart. Usually, all I see there is Energizer, though. I personally stay away from Energizer rechargeable now because I haven't had good experience with them. Compared to all other brands I've used, the Energizers have given me much fewer charge/discharge cycles before wearing out.
I recently got really lucky and went to a local battery shop and found Sanyo Eneloop “pre-charged” (i.e., low self-discharge) batteries. In the online hobbyist community, this brand seems to have a reputation of being very high quality, but they tend to be very hard to find.
