i only go to sephora like twice a year, and i never spend more than like $100...
but for MAC...i average about $300 a month (depends on the collection, if i need new foundation, etc.). since i was so smitten with lingerie and CD: icon, i dropped about $600 from the time lingerie came out to the end of jan...i'm also always updating the non-LE collection i have too, since i don't own a lot of MAC skincare, and i'm always adding certain things i'll see on people's FOTDs if i like it.
so yeah...a lot of my money is spent on MAC, but it's something i use daily and as of late, most of it isn't just the LE "trends", so it's not THAT impractical