I'm always interested in this question, so I'm cross-posting: what was the first album you ever bought?
I'd like to think I picked this up because I was precociously hip and cool, but really, I just liked the album cover. It was in the "cut-out" bin, where the store put all the stuff that wasn't moving, and everything was less than $5. A lifetime of loving Bjork began. I also ended up working at the same store for my very first job, the long-lost Kemp Mill Music.