The D3000 just like the D50, D70/S, D40/X, D60, and D5000 were never designed to be used with a grip. I looked into getting one for my D70S about 5 years ago and determined that the third party grips were more trouble than they were worth. The only advantage they provide is more surface area to hold the body and additional weight. I would also stay away from third party batteries. Good Luck and Enjoy your Nikons!
It takes about 10 seconds to change the battery, so getting a spare Nikon battery and carrying it in your bag it the way to go. Just keep the plastic short guard on the spare when you are not using it. Good Luck and Enjoy your Nikons!
cant speak for the d3000 but i bought one for my d5000 and dont regret it yes battery life is extended but better is the grip of the body i find i have more control, as to the shutter mine is fitted with a seperate one on the side and works dandy best £30 spent on ebay (came from china in 3 days)
Just wanted to comment on turning on the IR feature to use this grip. I don't have the grip, but use my IR remote quite a bit. If you go into the menu on the D3000, you can assign the Fn button to change the release mode. All I have to do to change the release is to press the Fn button and roll the Command Dial. Only takes a few seconds. Not that difficult to me.