I can do better than 4 Pleasureflushes
I have lots of other rare stuff including some old e/s such as Haze, Clone, Black Gold, Judy Blue, all 9 Colour Theory shadows and all 4 Chroma Snake Eyes shadows. I have full sized jars of purple matte, green matte, auburn, mustard, brass, bronze and copper pigments, (although some of the jars are only half full). I have a couple of rare discontinued jars of glitter too. I have a few rare l/s including Heatherette, Blue Eve, Sexie, Holidazzle, Rockin' Rudi all three Playboy lipsticks and both Playboy glitter creams. I also have some MAC jewelled stick-on tattoos, a stack of long discontinued wild MAC false lashes, a couple of Isabella Blow t-shirts, Hot + Sour paint, Dabble paint, a few d/c brushes, all 4 Diana Ross brushes...
As you say, rare is a relative term, so I've got a lot of stuff some people would class as rare but others wouldn't. I have a lot of the more recently discontinued "rare" stuff too, such as parrot, guacamole, lucky green, de menthe, moth brown, dainty cake l/s, strawberry blonde l/s, Blow l/s and the more recently d/c frost pigments in silver, gold, blue (original and RR), green and maroon, plus Coco Beach and All Girl. I've also got a few d/c brushes, a stack of palettes and quads, most of the glitter liners... etc etc
The thing is, though, MAC being MAC, my list of d/c stuff is a lot longer than my list of permanent stuff!! I used to have a list of my entire collection but I lost it when my iPaq decided to die on me. I'd post it if I still had it.
I should also note that I've been seriously collecting for more than 3 years now and when I was earning good money (before I had to give up work) I used to drop a fair bit on MAC. I have a big collection but I've certainly paid enough for it!