I'd recommend grabbing Energizer's 2500mah NiMH AA batteries from Walmart @ $10 for 4 of them. They last a long time and are of good quality (they are Sanyo cells, IIRC).
AAA...I can't really say much about that size of battery.
Maybe get the charger bundle for them too (though I have heard complaints that it uses a timer instead of a smarter charging system), but mine are working well with a Panasonic quick charger (~2hr). No idea what that charger does...