I'm going to answer this question even though I don't like MAC all that much (I prefer YSL, Chanel, and Dior). I've been collecting MAC for only about two years. However, when Liberty of London came out I went all out.
However, in my defense, it was released either a week or two before my birthday and I had a few gift cards I didn't use from Christmas. I didn't like the line that came out after the Holiday 2009 line. I think it was Warm & Cozy. I didn't buy anything. So, what I had been saving for that, I originally wanted shade sticks, got added to the pot. So, with Liberty I bought two of every shadow, two of every lipstick, both make up bags, and the scarf.
Now, I have regrets. I don't like most of the eyeshadows. I wish I had hoarded more of Bough Gray. This collection had some horrible eyeshadows IMO. I don't live close to a MAC. So, I bought them online. Honestly, Liberty of London has to be the second worst eyeshadow I've tried from MAC (the first being Gesso). I also don't like MAC make up bags. I ended up giving the smaller makeup bag to a friend. I only kept the larger one to store all the eyeshadows I don't use in. So, I feel like I wasted major money. I guess the only good thing is I love white. So, I like the packaging. So, besides for Bough Gray, I'm only going to be looking at the packaging. Most of them are still in the orginal boxes. As are most of the lipsticks. I only liked Peacocks and Petals.
I tend to hoard things. So, I can see myself stupid doing this again if the right MAC collection strikes me. Hopefully next time I'll have better luck.