I am looking into a battery grip when I do my camerma upgrade. I was surprised to see how expensive the grips are... about 180 for a 30D grip. Batteries aren't even included. I've enjoyed the concept of one (more battery life, the look, the feel) but it'll cost sooo much money! I need your opinions... what makes it "WORTH" the 200+ it will cost (grip + batteries)? Also, should I save 60 bucks by going with 2 off-brand batteries, rather than 2 CANON ones? Also, once the grip is on, is it stuck there, or can I remove it quick?