I got to 102 stars when there wasn't much more I could do, so I went ahead and beat the game. That Luigi sprite thing was horrible. I think I spent a good 3 hours trying to beat that thing. The other one that gave me a lot of grief was the Dreadnought galaxy's purple comet. I'm at 119 stars right now, and the only thing I have yet to beat is the "blow up the trash" thing in the Dreadnought galaxy. I've played that thing at least a hundred times and I don't think I've ever been close to getting them all.