Collecting stuff is kind of an exercise in discontentment. Of course, perhaps the same could be said of life as a whole. It's still a mystery what makes me feel this crazy.
I'm actually pretty content with life as whole too, for the most part at least. I do wish I was in better health and had more money, but I don't think those are unreasonable things to feel discontented about. At least I'm happy with my living situation and the people I have in my life.
The real trick is to sometimes look at the old collection. Just kind of breathe and be happy for what you have. In fact sometimes you just want to play what you have instead of dreaming about the next thing...especially since you didn't play the last thing...