As a kid, there was one figure I never got from the first kinder egg figure series I collected. My dad felt so sorry for me (I think he was more sad about it than me, actually...) that he bought a hole, sealed retail box of kinder egg just to make sure my brother and I would get all the figures in the next collection... Damn, we ate a lot of kinder egg! (We didn't get to eat them all at once though ) So I ended up with a pretty decent amount of each figure in that series. Lesson learned? Buy the hole box?
But seriously, I am considering buying a hole box, but I'll probably wait until somebody finds out the ratio of the figures I want the most. If they are the most common, I might only go with buying a handful.