I see the battery is listed as a 2100mAh - I see an extended one (4500mAh) that will obviously not work with the DX90 due to size - but there is a sale on ebay where you can get three 2900mAh batteries and a charger for twelve bucks. Is it just a higher capacity in the same size or a third size that also won't fit? I just like the idea of a battery charger having a hot battery waiting when the DX90 taps out.
http://www.ebay.com/itm/3-x-2900mAh-battery-USB-Charger-For-Samsung-Galaxy-S-3-III-i535-L710-T999-i9300-/390807370294?pt=US_Cell_Phone_PDA_Batteries&hash=item5afdef3a36