I'd go into a yarn shop looking for one thing and came out carrying a huge (half my height huge) bag full of skeins. Every. Single. Week.
I lost more than half my stash when I moved here and my brother gave/threw them away. The ones that I did manage to bring with me - for the most part - are still inside bins waiting to be knit.
For a few months (well...a year or so) after moving here, we were broke as broke can be, so buying yarn was only done when I got a good sale at one of the big chain craft stores.
Eventually my stash became more "fancy", with timid additions of natural fibers, hand dyed yarns and the like - all bought in very small quantities when I found a sale somewhere.
I didn't go crazy with busy, heavily variegated yarn for the sole reason that I didn't have the money to buy them. I'm kind of glad I didn't, as it's always hard to make those kinds of yarn work once knit.
We're now facing another "tighten the belts" times and I've decided to not buy yarn (unless extremely necessary). Truth be told, I've been avoiding buy yarn since last year or so, so it isn't a big deal for me.
As it stands, I have a decent (read: big) enough stash to do what I want/need to do and I don't want it to take over the basement.
I'll try to take pictures when we move. For now, I'm taking pleasure in throwing away labels of all used up yarns.