i was always into music since i was little, i recorded stuff off the radio and had bought tons of cassettes. however it was all basically Top40 radio stuff (which back in the 80's was quite good stuff actually; nice mix of alternative/new wave, heavy metal, rock, pop, even bits of hip hop/rap).
i didn't get serious about music until i bought this album on CD (which BTW was my first CD)
The Cure - Staring at the Sea.
i bought it in 1989, 4 years after it's release. at the time i was still well into heavy metal (Iron Maiden, Metallica, Megadeth, GnR, etc.) but the interest in metal was waning and wanted something more eclectic.. besides, i was always fascinated with the British indie new wavey alternative what-have-you side of things. another reason was that a friend of mine included "A Forest" and "Inbetween Days" in a mixed tape and i had to have a CD that had both songs, also hearing "Just Like Heaven" and "Lovesong" on the radio i knew i found my favourite band.
Staring at the Sea helped snowball my music buying habits, which still resonates to this day. it's probably the most important CD in my collection.