On a full battery charge I took (around) 200 pictures and over 10 minutes of video... and the meter didn't move at all. Basically, if you're getting less than 500 shots, either you have a bad battery (not terribly likely) or something in your process is draining the battery.
Though, I did notice on the charge that the battery had when I got it from the manufacture, I was only able to take maybe 100 charges before I had to charge it. But since then it's been full juice.
And personally, when you can get a 16GB card for less than $40... it's not worth getting 1/8 the size for 1/2 the price.