I'm not a makeup artist, so anything I buy is for my own use, and I try to keep what I own to a minimum. I guess an actual minimum would be zero makeup, but it's a creative outlet I enjoy a lot. So, for me, a minimal amount of makeup is a few basic products I wear everyday and a few other colour products for different looks.
I am drawn to a lot of products but I try to avoid anything I know I wouldn't finish. Personally I also avoid products with bad packaging as if I'm going to spend money on high-end makeup, I want to enjoy looking at it as well as using it. I used to have a budget for makeup spending each month, and now I set time limits between purchases instead (aiming for 2x a year).
Wondegondigo and Shameless Fripperies are bloggers I like because they address consumerism in makeup collection.