I've got a really cheap one for my 7D (about 39€), which I got from Ebay and I must say I'm pretty happy with it. It feels a little bit plasticy, the buttons aren't as nice as the one of the camera itself, as already said, the shutter button is very sensitive (you've got to get accustomed to it), but all in all it gets its job done pretty good for that amount of money - and it takes 2 batteries of course.