Then check out this aftermarket battery from Hong Kong, which is the same physical size as the stock battery but has a stated capacity of 2000mAh—300mAh more than stock—and is available for a measly $7.95 on eBay. How the battery actually performs is obviously debatable, but the price makes it easy to keep your expectations in check, especially when standard shipping and an external charger with fold-out prongs are both included for free.
Assuming the battery doesn't damage the phone, it almost seems silly not to spend $8 to get all of this, don't you think?
[eBay] Thanks, Chad S.!